power: bcl_peripheral: Use edge trigger interrupt

During boot, if there is a vbat interrupt from peripheral
the BCL can't mitigate the non-boot cores. Since
there is no mitigation that can be done, the hardware
still drives the interrupt leading to interrupt storm.

To avoid this move the interrupts to edge triggered.

CRs-Fixed: 806374
Change-Id: Ic8e5a98302e4da88e20d530681c070949d0fca81
Signed-off-by: Ram Chandrasekar <rkumbako@codeaurora.org>