[9fans] changes to the ARM SoC ports

[geoff@plan9.bell-labs.com]

booting(8) has been updated; take a look if you're using an ARM port.

On the Kirkwood SoCs (Sheevaplug and Openrd-client), USB now works.
Nemo was helpful fixing this, as usual.

One of the people here is working on using the Kirkwood crypto
acceleration hardware.

The OMAP3530 port is now available in /sys/src/9/omap.  It currently
runs on the IGEPv2 board.  The hardware can execute VFPv3
floating-point instructions, but 5[cal] don't generate them yet, so
floating-point is currently emulated.  USB isn't quite working yet.
Once it is, we should be able to use USB Ethernet and thus run on
Beagleboards.  The ohci and ehci controllers are seen, but no devices
yet.  There are several USB errata that need to be looked into.  From
the latest omap3530 errata:

- 3.1.1.130 only one usb dma channel (rx or tx) can be active
	at one time: use interrupt mode instead
- 3.1.1.144 otg soft reset doesn't work right
- 3.1.1.183 ohci and ehci controllers cannot work concurrently
- §3.1.3 usb limitations: all ports must be configured to identical speeds
	(high vs full/low)

This port is being made available now primarily as a basis for GSoC
students; we expect it to improve.

Rae McLellan of Bell Labs deserves thanks for helping to decrypt what
passes for hardware documentation these days.