pinctrl: Add api to enable/disable wakeup capability for a gpio

Add api to write to mpm wakeup registers to configure a gpio
as wakeup capable.

Change-Id: Ia11a22160394e76969200691cfaf8fb1505bf5c1
Signed-off-by: Rishabh Bhatnagar <rishabhb@codeaurora.org>
Signed-off-by: Elliot Berman <eberman@codeaurora.org>