msm: Display: Add support for backlight control on 8930 chipset.

Register the PMIC WLED trigger driver to control the backlight level
on 8930 chipset.

CRs-fixed: 339310
Change-Id: Ia73625cfeaa18f2515c81a4c128f98f9fb5c0b32
Signed-off-by: Chandan Uddaraju <chandanu@codeaurora.org>
2 files changed