msm: vidc: Add support for NV21 color format encoding

This change adds NV21 color format encoding support.

CRs-fixed: 448511
Change-Id: If26f1241a006e2d325668b8e189f6ff76df8e125
Signed-off-by: Deepak Verma <dverma@codeaurora.org>

Conflicts:
	drivers/video/msm/vidc/1080p/ddl/vcd_ddl_core.h
	drivers/video/msm/vidc/1080p/ddl/vcd_ddl_vidc.c
	drivers/video/msm/vidc/1080p/ddl/vidc.c
	drivers/video/msm/vidc/1080p/ddl/vidc_hwio_reg.h
	drivers/video/msm/vidc/common/enc/venc_internal.c