irqchip: qcom-pdc: add irqchip set/get state calls

Add irqchip calls to set/get interrupt state from the parent interrupt
controller. When GPIOs are renabled as interrupt lines, it is desirable
to clear the interrupt state at the GIC. This avoids any unwanted
interrupt as a result of stale pending state recorded when the line was
used as a GPIO.

Change-Id: Ibd551f84d8f6ae15b8d9702faeb585a69f283f6e
Signed-off-by: Maulik Shah <mkshah@codeaurora.org>
Signed-off-by: Lina Iyer <ilina@codeaurora.org>