davinci: Add MMC/SD support for DA830/OMAP-L137 EVM

Add pinmux settings, etc. to enable the MMC/SC hardware.

Signed-off-by: David A. Griego <dgriego@mvista.com>
Signed-off-by: Mark A. Greer <mgreer@mvista.com>
Signed-off-by: Kevin Hilman <khilman@deeprootsystems.com>