spmi: pmic-arb: Set PMIC Arbiter interrupt as a wakeup interrupt

Set the PMIC Arbiter as a wakeup interrupt in order to enable PMIC
peripherals (i.e. PON) to serve as wakeup interrupts.

Change-Id: I02738ab0fbdd953b73b3f043e35804882a19a92a
Signed-off-by: Kenneth Heitke <kheitke@codeaurora.org>