omap2: Update n8x0 defconfig to test multi-omap and DMA api changes

Recent DMA API changes broke compile for tusb6010. While
testing the fixes for tusb6010, I had to update the n8x0
defconfig quite a bit. Might as well merge it while at it
to make it more usable as we're using this to test the
multi-omap booting between V6 and V7 ARMs.

Also, anybody using n8x0 with a current kernel will most
likely want to mount root on the MMC instead of the onenand
to keep the Maemo install intact.

Enable I2C, REGULATOR, MMC, MFD, PM, and USB. Also change the root
to /dev/mmcblk0p2 instead of the onenand.

Signed-off-by: Tony Lindgren <tony@atomide.com>