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

QPNP Flash v2 LED driver supports the flash LED peripheral on
QTI PMICs like PMI8998, PM8150L and their derivatives to support
camera flash operation.

This is taken as a snapshot from msm-4.19 kernel
'commit 0873aa6e66d4 (" Merge "msm: ADSPRPC: Size check before
allocating memory from DMA")'.

Change-Id: If18cd60ba0e2ca2c463996e65216f02d21e6fd76
Signed-off-by: Kiran Gunda <kgunda@codeaurora.org>