Wandboard support

[Ian Lepore]

As of r257489 we now have some support for i.MX6 in general and
Wandboard specifically.  There is much work to do, especially in the
area of clock and power management and pinmux control, and someone other
than me will have to look towards graphics and sound support (I have no
skills in those areas).

Things that work:

      * Single core (even on the multicore boards).
      * Boots to fully functional multi-user mode.
      * Gigabit ethernet
      * SD Card
      * USB
      * UART (serial console)

I'm not sure what the state of SMP for ARM is in general.  I've been
more focused on getting the major imx devices working first.  We're
about to the point where it's time to give it a try I think.  :)

I haven't tried using ubldr yet, I've just been directly booting the
kernel via tftp, and nfs-mounting the root filesystem.  I have tested
that the boards will boot from and run from sdcard just fine, and I
expect the same would be true for USB drives, but I haven't tried that.

The kernel is compiled to load at 0x12000000, which is NOT the default
address in the board's u-boot config.  I set the kernel to a different
address so that ubldr could load at the board's $loadaddr.

-- Ian