spmi-pmic-arb: do not mask irq which owned by APSS

As a workaround for interrupt that got stack at boot
time and could not be cleared by APPS, the driver reads
the interrupt accumulator at probe time and later
masks the corresponding interrupt, thinking that they
are stack.
However, there are valid cases where an interrupt that
is owned by APSS fire at boot time and seen by the probe.

This patch unmasks bits of interrupts that are present
in probe time in case they owned by APSS.

Change-Id: I534e69ee6cf6cc113101cc89823b1784821b4a8b
Signed-off-by: Gilad Avidov <gavidov@codeaurora.org>