media: v4l2: Add description for V4L2_PIX_FMT_AV1 in v4l_fill_fmtdesc()

media: v4l2: Add description for V4L2_PIX_FMT_AV1 in v4l_fill_fmtdesc()

Add a descriptive string for the AV1 pixel format to v4l_fill_fmtdesc(),
enabling proper reporting of AV1 support via VIDIOC_ENUM_FMT.

Reviewed-by: Bryan O'Donoghue <bryan.odonoghue@linaro.org>
Reviewed-by: Nicolas Dufresne <nicolas.dufresne@collabora.com>
Reviewed-by: Hans Verkuil <hverkuil+cisco@kernel.org>
Signed-off-by: Deepa Guthyappa Madivalara <deepa.madivalara@oss.qualcomm.com>
Tested-by: Val Packett <val@packett.cool>
Signed-off-by: Bryan O'Donoghue <bod@kernel.org>
Signed-off-by: Hans Verkuil <hverkuil+cisco@kernel.org>