Add menu control for VP9 codec levels. A total of 14 levels are
defined for Profile 0 (8bit) and Profile 2 (10bit). Each level
is a set of constrained bitstreams coded with targeted resolutions,
frame rates, and bitrates.

The definitions have been taken from webm project [1].

[1] https://www.webmproject.org/vp9/levels/Signed-off-by: Stanimir Varbanov <stanimir.varbanov@linaro.org>
Reviewed-by: Nicolas Dufresne <nicolas.dufresne@collabora.com>
Reviewed-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>