leds: add support for QTI flash LED driver

QTI flash LED driver supports flash LED module on PM8350C. It is used
for illumination by camera sensor and also for torch application.

Change-Id: Iaa4754591e37db48c0ab360cdf4660d50c908337
Signed-off-by: Shyam Kumar Thella <sthella@codeaurora.org>