[ARM] pxa: merge assignment of set_wake into pxa_init_{irq,gpio}()

To further clean up the GPIO and IRQ structure:

1. pxa_init_irq_gpio() and pxa_init_gpio() combines into a single
   function pxa_init_gpio()

2. assignment of set_wake merged into pxa_init_{irq,gpio}() as
   an argument

Signed-off-by: eric miao <eric.miao@marvell.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>