spmi: qpnp-int: Support wake interrupts

The irq framework already supports wakeup interrupts. We just
need to provide a dummy irq_set_wake so the framework does not
return an error. Also specify the MASK_ON_SUSPEND flag so that
non-wake interrupts are masked on suspend.

Change-Id: I7fa5717d79467e22647606c3ee93373a2bffc547
Signed-off-by: Michael Bohan <mbohan@codeaurora.org>