media: hevc: Add fields and flags for hevc PPS

Add fields and flags as they are defined in
7.4.3.3.1 "General picture parameter set RBSP semantics of the
H.265 ITU specification.

Signed-off-by: Benjamin Gaignard <benjamin.gaignard@collabora.com>
Reviewed-by: Ezequiel Garcia <ezequiel@collabora.com>
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>