media: hantro: Introduce G2/HEVC decoder

Implement all the logic to get G2 hardware decoding HEVC frames.
It supports up level 5.1 HEVC stream.
It doesn't support yet 10 bits formats or the scaling feature.

Add HANTRO HEVC dedicated control to skip some bits at the beginning
of the slice header. That is very specific to this hardware so can't
go into uapi structures. Computing the needed value is complex and requires
information from the stream that only the userland knows so let it
provide the correct value to the driver.

Signed-off-by: Benjamin Gaignard <benjamin.gaignard@collabora.com>
Co-developed-by: Adrian Ratiu <adrian.ratiu@collabora.com>
Signed-off-by: Adrian Ratiu <adrian.ratiu@collabora.com>
Co-developed-by: Ezequiel Garcia <ezequiel@collabora.com>
Signed-off-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>