ARM: dts: msm: remove brightness setting from r61318/r63417 initial code

Brightness value should not be set in panel initialization code as without
that panel will show grey screen before showing fb data. Fix this by not
setting brightness value.

Change-Id: Ic0460e2c53d1c50268ad50d51058119bd303ee7b
Signed-off-by: Shuo Yan <shuoy@codeaurora.org>