[PATCH] gpio_keys driver shouldn't be ARM-specific

The gpio_keys driver is wrongly ARM-specific; it can't build on
other platforms with GPIO suport.  This fixes that problem.

Signed-off-by: David Brownell <dbrownell@users.sourceforge.net>
Cc: Dmitry Torokhov <dtor@mail.ru>
Cc: pHilipp Zabel <philipp.zabel@gmail.com>
Cc: Haavard Skinnemoen <hskinnemoen@atmel.com>
Cc: Russell King <rmk@arm.linux.org.uk>
Cc: Richard Purdie <rpurdie@rpsys.net>
Cc: Ben Nizette <ben.nizette@iinet.net.au>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>