ARM: OMAP5: Power: Add more functionality to Palmas driver

Add some useful functions, and the corresponding definitions.

Add support for powering on the dra7xx_evm SD/MMC LDO
(courtesy Lokesh Vutla <lokeshvutla@ti.com>).

Signed-off-by: Lubomir Popov <lpopov@mm-sol.com>
Reviewed-by: Tom Rini <trini@ti.com>