gpio/omap: cleanup set_gpio_triggering function

Getting rid of ifdefs within the function by adding register offset intctrl
and associating OMAPXXXX_GPIO_INT_CONTROL in respective SoC specific files.
Also, use wkup_status register consistently instead of referring to wakeup
clear and wakeup set register offsets. Get rid of cpu_is_xxxx checks in
set_gpio_trigger() using irqctrl.

Signed-off-by: Charulatha V <charu@ti.com>
Signed-off-by: Tarun Kanti DebBarma <tarun.kanti@ti.com>
Reviewed-by: Santosh Shilimkar <santosh.shilimkar@ti.com>
Acked-by: Tony Lindgren <tony@atomide.com>
Reviewed-by: Kevin Hilman <khilman@ti.com>
Signed-off-by: Kevin Hilman <khilman@ti.com>