leds: qpnp-flash-v2: Add support for led_fault_irq

Add support to receive and process the led_fault_irq to
detect short_circuit and open_circuit faults. Also, add
support to read all led_status registers in the irq handler.

CRs-Fixed: 1024187
Change-Id: I6941660484ea8b27377c668d1e7d815d52e83d83
Signed-off-by: Devesh Jhunjhunwala <deveshj@codeaurora.org>