GFX-Display: Set backlight duty factor to 127 for DV10

GFX-Display: Set backlight duty factor to 127 for DV10

BZ: 24890

From panel spec, we don't found exact saying about maximum value of backlight
duty, but per the debug resust, when set it to 127 instead of 255, it can work.

Change-Id: Ide08eb912f1e6e4882db4630c68ef181b815ed12
Signed-off-by: Geng Xiujun <xiujun.geng@intel.com>
Reviewed-on: http://android.intel.com:8080/36338
Reviewed-by: Ai, Ke <ke.ai@intel.com>
Reviewed-by: Xu, Randy <randy.xu@intel.com>
Reviewed-by: Tong, BoX <box.tong@intel.com>
Tested-by: Tong, BoX <box.tong@intel.com>
Reviewed-by: buildbot <buildbot@intel.com>
Tested-by: buildbot <buildbot@intel.com>