Drivers: GPIO: Allow AW9523 to be used without interrupts

There will be an compilation error if there is no interrupt GPIO defined
in the device tree file, as parts of the config and data structs
have #if that depends on the presence of interrupt GPIO.

Use the same #if constructs also on the functions that use those
structs.

Signed-off-by: Jonas Berg <jonas.s.t.berg@gmail.com>