media: hantro: Add support for MPEG-2 decoding on RK3328

Add necessary bits to support MPEG2 decoding on RK3328.

Signed-off-by: Jonas Karlman <jonas@kwiboo.se>
Signed-off-by: Ezequiel Garcia <ezequiel@collabora.com>
Signed-off-by: Philipp Zabel <p.zabel@pengutronix.de>
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org>