Revert "video: msm_fb: Ensure backlight is scaled atomically"

This reverts commit 5efdbf5b5b308a18d80ff6eae6d391c3a620f0e3.

Conflicts:
	drivers/video/msm/msm_fb.c

Change-Id: Ifd4261a971fbc1f0336f73295bbf11187f2884a6