mfd: arizona: Suppress needless calls to the primary IRQ

We can read back if the primary IRQ is asserted from the register map,
meaning that we can suppress polling of the interrupt status registers
when only the AoD IRQ domain is asserting.

Signed-off-by: Mark Brown <broonie@opensource.wolfsonmicro.com>
Signed-off-by: Samuel Ortiz <sameo@linux.intel.com>