encoder:h264: Fix the check for packed-header support
encoder:h264: Fix the check for packed-header support

Use VA_ENC_PACKED_HEADER_* definition for checking.

Signed-off-by: Sreerenj Balachandran <8526e100bdc7a12d85af109c9f42b86756e50e67@intel.com>

gbeauchesne/gstreamer-vaapi,gbeauchesne/gstreamer-vaapi,gbeauchesne/gstreamer-vaapi