vc04_services: vchiq-mmal: Add defines for mmal_es_format flags

There is a flags field in struct mmal_es_format, but the defines
for what the bits meant weren't included in the headers.
For V4L2_PIX_FMT_NV12_COL128 support we need them, so add them in.

Signed-off-by: Dave Stevenson <dave.stevenson@raspberrypi.com>