gralloc: Fix NV12_ENCODEABLE allocation

Targets having the venus core have the same allocation and stride
requirements for HAL_PIXEL_FORMAT_NV12_ENCODEABLE as the
HAL_PIXEL_FORMAT_YCbCr_420_SP_VENUS format.

Change-Id: Ie5ab8db6639dfa791c5be0161cde6140c3dae779
1 file changed