There is a PWRBTN# input pin exposed on a Q7 connector. The pin
is routed to a GPIO0_A1 through a diode. Q7 specification describes
the PWRBTN# pin as a Power Button signal.
Configure the pin as KEY_POWER, so it can function as power button and
trigger device shutdown.
Signed-off-by: Daniel Semkowicz <dse@xxxxxxxxxxxxx>