[zircon][usb-request-cleanup]Remove bti_handle from usb-request

The bti_handle is used only during the physmap which is used only at the
usb infrastructure level and not by the client drivers. This change removes
the bti handle from usb_request_t, and also removes the need for it beeing needed
during the usb_request_alloc. In a later changeset, clients will be using
the usb_request_alloc directly from the usb-request library and not via
the protocol op. This changeset is in preparation for that to work.

Test: Full build. Netbooting on vim2. Plugged in a usb-mass-storage
device and verified lsusb works as expected.

Change-Id: I158917a9cfec1c3b0f2b9ec905c17dbfcc6ecbc7

[zircon][usb-request]Move usb-request.c out of ulib/ddk

The motivation behind this changes is that eventually system/ulib/ddk
should go away and parts of it should move to where they belong.
This changeset moves usb-request.c, usb-request-test.c out of the ulib/ddk
to system/dev/lib/usb-request. This library is internal for system/dev/usb
and all its fucntionality will be exposed via the usb protocol and the
usb-function protocol to the client drivers.

Test: Build. Basic Sanity test on vim2. Ran usb-request-tests using
runtests /boot/test/ddk/driver-tests

Change-Id: Ia62693f51046b9c93e4a4b9abfd25286b0d9b972

[dev][usb] Add support for automatic zero length packets

Set send_zlp flag on usb_request_t if you want zero length packets
sent automatically when transfer length is a multiple of max packet size.

ZX-1952 #done

Change-Id: I78e1cf3231179ec77b20b1ca95e5b765e7ed5dac

[ddk][io-buffer] Rename callsites of io_buffer_init*_with_bti

ZX-1804 #comment Move all zircon callsites to final name

Change-Id: Ie35de5654841e84653582126dc1f976664c0f49d

[dev][usb][dwc3] Switch to io_buffer_init_with_bti()

Change-Id: Ieb7672516d02d6d84efeb2fa3cd798329f1d0e15

[ddk][usb-request] Remove usb_request_phys()

USB request buffers are always non-contiguous,
and io_buffer_phys() now asserts when called on non-contiguous buffers.
So we should now require using usb_request_phys_iter_init()
and usb_request_phys_iter_next() instead.

The dwc2 and dwc3 drivers do not yet support scatter/gather
and require all transactions to fit in a page,
but that is a separate problem to fix.

Change-Id: Ib25df2d5dcea9d2ae8cda4c80783f4b5a6d82c00

[dev][usb][dwc3] Allocate fifo as IO_BUFFER_CONTIG

This is a page in size so it doesn't normally matter, but since
dfe61352d7d58857e2ca9389e08a204c0d3042e0 this was causing an assert.

Change-Id: Ia995d8a47c1b9cff169af5cd864a42dced16dce6

[ddk][iotxn] remove iotxn.c and iotxn.h

Change-Id: I569b02d1ac437a0db3968feaa8d05980a4def236

[dev][usb][dwc3] Use zx_cache_flush instead of zx_vmo_op_range for cache management

Change-Id: I8246d14f9f63e9db34e8cd4282700f015ef73853

[dev] Remove some unnecessary contiguous iotxns and io-buffers

Change-Id: I2089b2b1df8ec77216fc1a8d8f29729ba09fd5ce

[ddk] rename dprintf() to zxlogf() to avoid conflicts

dprintf is still defined by ddk/debug.h but with a deprecation warning

Change-Id: I00b34803571c468007e069c1da6a292feba2bc3c

[dev][usb][dwc3] Migrate to usb_request

Adds request_queue to dci_protocol

Change-Id: I7b9d0d533a172c2fd7adc78c46ec1c4746c7e0a4

[ddk][io-buffer] Add support for creating non-contiguous IO buffers

IO buffers are now non-contiguous by default.
Buffers are allocated contiguously if the IO_BUFFER_CONTIG flag is passed
and the buffer size is greater than one page.

Change-Id: I5d069b80df3bcbe9b148639c6c2b60f2442109a9

[zx] Magenta -> Zircon

The Great Renaming is here!

Change-Id: I3229bdeb2a3d0e40fb4db6fec8ca7d971fbffb94

[dev][usb][dwc3] First cut at DWC3 USB controller driver

Implements basic peripheral mode support for DWC3

Still to do for peripheral mode:
- USB 3 support
- Isochronous endpoint support
- Scatter/gather support
- OTG support for better connect/disconnect detection

and beyond peripheral mode:
- USB host support (we will layer the XHCI driver on top of this driver for host support)
- role switching between host and peripheral mode
- power management

Change-Id: I028f7af18f4434e17e1fe5fe36f0d1a83a409e55