Copy head (r256279) to stable/10 as part of the 10.0-RELEASE cycle.

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

Another overhaul of the CPSW driver for BeagleBone

Major changes:
* Finally tracked down the flow control setting that
seems to have been causing TX stalls and watchdog timeouts
* RX and TX paths now share a lot more code
* TX interrupt is no longer used; we instead GC finished
tx queue entries at the bottom of the start routine.
* TX start now queues fragmented packets directly; it only
invokes defrag() for occasional very fragmented packets.
* "sysctl dev.cpsw" dumps controller statistics and queue counts
* Host Error Interrupt will give extensive debugging information
if the controller chokes on the queued data.

While trying to track down the root cause for
TX stalls in this driver, I've also had some
time to evaluate the effectiveness of different
watchdog strategies.

This is the latest attempt, which consolidates
all of the watchdog logic in one place and
consistently detects TX stalls and resets within
a couple of seconds.

Overhauled CPSW driver for TI CPSW Ethernet module
(as used in AM335x SoC for BeagleBone).

Among other things:
* Watchdog reset doesn't hang the driver.
* Disconnecting cable doesn't hang the driver.
* ifconfig up/down doesn't hang the driver
* Out-of-memory no longer panics the driver.

Known issues:
* Doesn't have good support for fragmented packets
(calls m_defrag() on TX, assumes RX packets are never fragmented)
* Promisc and allmulti still unimplimented
* addmulti and delmulti still unimplemented
* TX queue still stalls (but watchdog now consistently recovers in ~5s)
* No sysctl monitoring
* Only supports port0
* No switch configuration support
* Not tested on anything but BeagleBone

Committed from: BeagleBone

Merging of projects/armv6, part 10

- Support for Texas Instruments SoCs:
- AM335x
- OMAP4

- Kernel configs, DTS for Beaglebone and Pandaboard

Submitted by: Ben Gray, Damjan Marion