[MMC] Add OMAP MMC host driver

Adds OMAP MMC driver.

Signed-off-by: Juha Yrjl <juha.yrjola@nokia.com>
Signed-off-by: Tony Lindgren <tony@atomide.com>
Signed-off-by: Carlos Aguiar <carlos.aguiar@indt.org.br>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>