spmi-pmic-arb: ignore faulty interrupt bits

Due to some faulty HW/SW interaction during boot loader
time, the first accumulator bit may be incorectly set.
When the peripheral represented by this bit is not
owned by the application processor, it stays set forever,
confusing the interrupt controller to think that it
get interrupted by that peripheral when it isn't.
To amend this problem, we read the accumulator value
at boot time and compare that value to the accumulator
when new interrupt is handled. If a bit reperesenting
a peripheral was set at probe time, then it is ignored.

Change-Id: Iab3d70d6c63520ac7be1e77aba113cf5f46ec003
Signed-off-by: Gilad Avidov <gavidov@codeaurora.org>