spmi: pmic-arb: cleanup unrequested irqs

We see a unmapped irqs trigger right around bootup. This could
likely be because the bootloader exited leaving the interrupts
in an unknown or unhandled state.  Ack and mask the interrupt
if one is found. A request_irq later will unmask it and also
setup proper mapping structures.

Also the current driver ensures that no read/write transaction
is in progress while it makes changes to the interrupt regions.
This is not necessary because read/writes over spmi and arbiter
interrupt control are independent operations. Hence, remove the
synchronized accesses to interrupt region.

Signed-off-by: Abhijeet Dharmapurikar <adharmap@codeaurora.org>
Signed-off-by: Kiran Gunda <kgunda@codeaurora.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>