omxvideoenc: Add an unimplemented mapping for RGBA formats
omxvideoenc: Add an unimplemented mapping for RGBA formats

Add some pixel formats mappings for 2 RGBA formats. Not yet
implemented in the buffer input code though, so no effect for now.

CapOM/gst-omx,GStreamer/gst-omx,CapOM/gst-omx,GStreamer/gst-omx,varunkumara/test-repo,CapOM/gst-omx,varunkumara/test-repo,GStreamer/gst-omx,varunkumara/test-repo