media: hantro: vp9: use double buffering if needed

Some G2 variants need double buffering to be enabled in order to work
correctly, like that found in Allwinner H6 SoC.

Add platform quirk for that.

Reviewed-by: Andrzej Pietrasiewicz <andrzej.p@collabora.com>
Signed-off-by: Jernej Skrabec <jernej.skrabec@gmail.com>
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>