msm: camera: Fix LED current for Dual LED support

This change is required for dual LED usecase where
flash/torch current = 0 is valid value. With this
change, current = 0 from user is treated as LED off
instead of LED on with default current.

Change-Id: I3d35e58bba38ba3cdf85aa24f0588f3a4c1219ac
Signed-off-by: Ivan Tiyanov <ivant@codeaurora.org>
Signed-off-by: Xu Han <hanxu@codeaurora.org>