spmi: pmic-arb: support show_resume_irq

show_resume_irq is used to debug interrupts that cause wakeup.
Support it for spmi arbiter's interrupt controller.

Change-Id: I52d51c09d7ff316248542c84a1cd65a28e2283da
Signed-off-by: Abhijeet Dharmapurikar <adharmap@codeaurora.org>