irqchip: qcom: pdc: Add irq_set_wake support to pdc irqchip

GIC driver started supporting irq_set_wake call and stores
wakeup capable irq in wakeup_irqs with commit
fc8e11b2.

Since PDC is currently not forwarding irq_set_wake calls
to its parent GIC, device is not able to wake up from
suspend since no wakeup capable IRQ is present in GIC's
wakeup_irqs.

Add support in PDC irq_chip to forward irq_set_wake calls
to its parent GIC to resolve this.

Change-Id: Ib151658a551364545a67e82b07520fe3bf19373d
Signed-off-by: Raghavendra Kakarla <rkakarla@codeaurora.org>