msm8x60_celox: Add panel undervolt interface

This reverts commit b9d1d7e0accccf06f008351eddefaa38fb3749dd.

Conflicts:
	arch/arm/mach-msm/include/mach/board.h
msm8x60_celox: panel_uv: Minor clean-up

Signed-off-by: Sultanxda <sultanxda@gmail.com>
msm8x60_celox: panel_uv: Remove redundant if-statement

derpty derp derp

Signed-off-by: Sultanxda <sultanxda@gmail.com>