MFC r307518:
Fix device delete child function.

When detaching device trees parent devices must be detached prior to
detaching its children. This is because parent devices can have
pointers to the child devices in their softcs which are not
invalidated by device_delete_child(). This can cause use after free
issues and panic().

Device drivers implementing trees, must ensure its detach function
detaches or deletes all its children before returning.

While at it remove now redundant device_detach() calls before
device_delete_child() and device_delete_children(), mostly in
the USB controller drivers.

Tested by: Jan Henrik Sylvester <me@janh.de>
Reviewed by: jhb
Differential Revision: https://reviews.freebsd.org/D8070

Copy head@r302406 to stable/11 as part of the 11.0-RELEASE cycle.
Prune svn:mergeinfo from the new branch, as nothing has been merged
here.

Additional commits post-branch will follow.

Approved by: re (implicit)
Sponsored by: The FreeBSD Foundation

Add 64-bit DMA support in the XHCI controller driver.
- Fix some comments and whitespace while at it.

MFC after: 1 month
Submitted by: marius@

Hook the ISP/SAF1761 driver into MIPS kernel builds.
- Update FDT file for BERI DE4 boards.
- Add needed kernel configuration keywords.
- Rename module to saf1761otg so that the device unit number does not
interfere with the hardware ID in dmesg.

Sponsored by: DARPA, AFRL

Optimise the ISP/SAF1761 driver:
- Use an interrupt filter for handling the data path interrupts. This
increases the throughput significantly.
- Implement support for USB suspend and resume in USB host mode.

Sponsored by: DARPA, AFRL

Fixes for ISP/SAF1761 host mode:
- Make the USB hardware skip PTDs which are not allocated.
- Peek host memory twice. Sometimes the PTD status is incorrectly
returned as zero.
- Ensure the host channel is always freed when software TD
is completing.
- Add correct configuration of interrupt polarity and type.
- Set CERR to 2 for asynchronous traffic to avoid having to
reactivate the PTD when a NAK token is received.
- Fix detection of STALL PID.

Sponsored by: DARPA, AFRL

- Correct bus space resource type for register access.
- Add configuration of interrupt type and polarity via FDT.

Sponsored by: DARPA, AFRL

Rename "saf1761_dci_xxx" into "saf1761_otg_xxx" to reflect that this
driver supports both host and device side mode.

Sponsored by: DARPA, AFRL

- Add flattended device tree probe-, attach- and detach code for the
SAF1761 driver, compatible to existing Linux based FDT tables for the
same hardware.

Sponsored by: DARPA, AFRL

Implement USB device side driver code for SAF1761 and compatible
chips, based on datasheet and existing USS820 DCI driver. This code is
not yet tested.

Sponsored by: DARPA, AFRL

Create driver file templates, kernel module Makefile and add initial
version of register definitions for ISP1761 and SAF1761 compatible
chips.

Sponsored by: DARPA, AFRL