ARM: dts: msm: Update msm8939 skuk panel gamma setting

Update msm8939 skuk panel gamma setting to resolve the display contrast
issue which caused some of thin line can not be seen on screen.

Change-Id: I322ffc9c58d6c7ef436fb08b7e3a3e39af74c87e
Signed-off-by: feifanz <feifanz@codeaurora.org>