media: verisilicon: AV1: Correct some sizes/positions on register fields

Some fields aren't well positioned or with an incorrect size inside the
hardware registers. Fix them.

This doesn't impact the Fluster score.

Fixes: 727a4006 ("media: verisilicon: Add Rockchip AV1 decoder")
Signed-off-by: Benjamin Gaignard <benjamin.gaignard@collabora.com>
Reviewed-by: Nicolas Dufresne <nicolas.dufresne@collabora.com>
Signed-off-by: Sebastian Fricke <sebastian.fricke@collabora.com>
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>