video: msm: Move histogram disable to before panel off

Histogram expects the display to be on while running, thus moving its
disable call to before disabling the panel timing generator ensures this
assertion.

Change-Id: I308b3e0c24f0111fb8549d0a0ae025910d649b75
Signed-off-by: Carl Vanderlip <carlv@codeaurora.org>

Conflicts:

	drivers/video/msm/mdp4_overlay_dsi_video.c
	drivers/video/msm/mdp4_overlay_lcdc.c

Signed-off-by: Pravin Tamkhane <pravint@codeaurora.org>