ARM: multi_v7: Enabled omap4430 sdp nfsroot

By adding support for OCP2SCP, SPI and KS8851 I can also boot test
multi_v7_defconfig easily.

Note that if using an older u-boot, CONFIG_ARM_ATAG_DTB_COMPAT=y
may also be needed for the appended DTB based booting.

Reviewed-by: Felipe Balbi <balbi@ti.com>
Signed-off-by: Tony Lindgren <tony@atomide.com>