This commit fixes the names and constants of the reserved NAL units
with nal_unit_type 22 resp. 23. They were "IRAP_IRAP_VLC2x", but are
actually "RSV_IRAP_VLC2x".

This also required a change to cbs_h265_syntax_template.c.
Reviewed-by: Anton Khirnov <anton@khirnov.net>
Signed-off-by: Andreas Rheinhardt <andreas.rheinhardt@gmail.com>