spmi: spmi-pmic-arb: Fix hw_irq overflow

Currently, when handling the SPMI summary interrupt, the hw_irq
number is calculated based on SID, Peripheral ID, IRQ index and
APID. This is then passed to irq_find_mapping() to see if a
mapping exists for this hw_irq and if available, invoke the
interrupt handler. Since the IRQ index uses an "int" type, hw_irq
which is of unsigned long data type can take a large value when
SID has its MSB set to 1 and the type conversion happens. Because
of this, irq_find_mapping() returns 0 as there is no mapping
for this hw_irq. This ends up invoking cleanup_irq() as if
the interrupt is spurious whereas it is actually a valid
interrupt. Fix this by using the proper data type (u32) for id.

CRs-Fixed: 2357600
Change-Id: I451e33d61e063d3a9381c2b43767946117a5bbb9
Signed-off-by: Subbaraman Narayanamurthy <subbaram@codeaurora.org>