ARM: 6175/1: nomadik-gpio: implement set_wake

So that set_irq_wake() works.

Cc: Alessandro Rubini <rubini@unipv.it>
Acked-by: Linus Walleij <linus.walleij@stericsson.com>
Signed-off-by: Rabin Vincent <rabin.vincent@stericsson.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>