msm: camera: uapi: Add support for precise flash on duration

Precise flash needs the data for time on duration from UMD.
Add the attribute to fill in by UMD. Also, updating the Macro
for the max led trigger from 3 to 2 as there are only two
physical LED channel is available.

CRs-Fixed: 2633194
Change-Id: I641e1ab42e59bc251d33a1e1dd0dff83afb5b7fb
Signed-off-by: Jigarkumar Zala <jzala@codeaurora.org>