ARM: pxa: fix gpio wakeup setting

In 3.3, gpio wakeup setting was broken. The call
enable_irq_wake() didn't set up the PXA gpio registers
(PWER, ...) anymore.

Fix it at least for pxa27x. The driver doesn't seem to be
used in pxa25x (weird ...), and the fix doesn't extend to
pxa3xx and pxa95x (which don't have a gpio_set_wake()
available).

Signed-off-by: Robert Jarzmik <robert.jarzmik@free.fr>
Signed-off-by: Haojian Zhuang <haojian.zhuang@gmail.com>