[ARM] 3561/1: Poodle: Correct the MMC/SD power control

Patch from Richard Purdie

Correct the Poodle power control for the MMC/SD port. Also
add write protection switch support.

Signed-off-by: Richard Purdie <rpurdie@rpsys.net>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>