Add OMAP spi100k driver

This change adds the OMAP SPI 100k driver created by
Fabrice Crohas <fcrohas@gmail.com>.  This SPI bus is found on
OMAP7xx-series smartphones, and for many, the touchscreen is
attached to this bus.

The lion's share of the work was done by Fabrice on this driver --
I am merely porting it from the Linwizard project on his behalf.

Signed-off-by: Cory Maccarrone <darkstar6262@gmail.com>
Signed-off-by: Grant Likely <grant.likely@secretlab.ca>