OMAP4: keypad: Add the board support

-Add the platform changes for the keypad driver
-Register keyboard device with hwmod framework.

Signed-off-by: Syed Rafiuddin <rafiuddin.syed@ti.com>
Signed-off-by: Abraham Arce <x0066660@ti.com>
Signed-off-by: Shubhrajyoti D <shubhrajyoti@ti.com>
Signed-off-by: Tony Lindgren <tony@atomide.com>