leds: qpnp-flash-v2: Add support for droop and fault detection

Add support for configuring the following features available
in flash LED:
	1. VPH droop detection
	2. Short circuit fault detection
	3. Open circuit fault detection

CRs-Fixed: 1024187
Change-Id: I982e51ba62f0a75d1dcd3ef30e5d1249c970ffde
Signed-off-by: Devesh Jhunjhunwala <deveshj@codeaurora.org>