media: tegra-video: Update format lookup to offset based

Tegra VI supported video formats are more for non TPG and there
can be multiple pixel formats for the same media bus format.

This patch updates the helper function for format lookup based on
mbus code from pre-defined Tegra supported format list to look from
the specified list index offset.

Offset based look up is used with sensor device graph (non TPG)
where format enumeration can list all supported formats for the
specific sensor mbus codes.

Signed-off-by: Sowjanya Komatineni <skomatineni@nvidia.com>
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>