Beaglebone USB driver (Mentor Graphics OTG)

[Oleksandr Tymoshenko]

Hello,

This is first iteration of Host Mode support for Mentor Graphics
OTG USB controller. I tested it by building kernel with USB memory
stick mounted as /usr/obj, resulting kernel was bootable and worked fine.
I reused some ideas (mostly for channel-management) from
DWT OTG driver.

Some pieces are still missing:
- Support for SPLIT transactions, I don not have high speed hub
     right now to test it, but implementing it should be really 
straighforward.
- Isochronous transfers. I do not have hardware to test this. Does
     anybody have any suggestion about simple use case?
- Control Data OUT transaction
- Wrapper for atmel HW has not ben synced with new core logic requirements
     yet

Please review and test. I tested it only with gcc-built kernel/world. 
Now when
first iteration is finished I'm going to update all my boards to new 
world order
(clang/EABI) and re-test this stuff.

Patch:
http://people.freebsd.org/~gonzo/arm/patches/beaglebone-musb.diff