gralloc: Add support for lock_ycbcr

Fill the android_ycbcr struct for HAL_PIXEL_FORMAT_YCbCr_*_888
formats.

Change-Id: If0c7abf5e206bf982ad333da2dae57cbac302733

Conflicts:
	modules/display-caf/libgralloc/gralloc.cpp
	modules/display-caf/libgralloc/mapper.cpp