[PATCH] Corgi: Add MMC/SD write protection switch handling

Add MMC/SD write protection switch handling for the Corgi platform

Signed-off-by: Richard Purdie <rpurdie@rpsys.net>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>