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

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

Use the pin number rather than the hybrid pin number + name.

BWCT boards can have 128MB SDRAM.

MFp4:
Add support for the CENTIPAD board (http://www.harerod.de/centipad/index.html)
(which is a very cool, very small ARM board)
Add support for KB9202B (it has different memory)
Make BOOT_FLAVOR settable
Minor cleanup nits

Approved by: re@

RTC_TIMR's RTC_SEC field is BCD. That makes it unsuitable for
GetSeconds(). Instead, use CRTR register shifted right 15. This
gives us a range of 32 seconds we can do for timeout.

Shift to using == rather than < or > for calculating the timeout,
since if we can't read the ST_CTRT register twice in a second we have
even bigger problems to worry about, and == deals with the 'wrap'
issue.

This lets me type at the boot2 prompt again! Woo Hoo!

Bogusness noticed by: tisco
Pointy Hat to: That silly imp guy

MFp4: boot on KB9202 correctly. Also, reduce the size of the SD/MMC driver
somewhat.

MFp4:

Massive update. The highlights:
o dramatically cut memory usage by writing better, less intertwingled
code.
o implement booting off mmc/sd cards (sd only tested one at the moment)
o start to split out board specific stuff for boot2.

MFp4:

On the KB9202 go ahead and enable the flash controller so the boot
loader can access the parallel flash.

MFp4 (checkpoint of work in progress):

o Use a directory layout that is more akin to the i386 boot layout.
o Create a libat91 for library routines that are used by one or more
of the boot loaders.
o Create bootiic for booting from an iic part.
o Create bootspi for booting from an spi part.
o Optimize the size of many of these routines (especially emac.c). Except
for the emac.c optimizations, all these have been tested.
o eliminate the inc directory, libat91 superceeds it.
o Move linker.cfg up a layer to allow it to be shared.