staging: media: tegra-video: fix typos in comment

Add "skip" in "so we can *skip* the current channel" or it doesn't make
sense.

Also add articles where appropriate to fix English grammar.

Signed-off-by: Luca Ceresoli <luca.ceresoli@bootlin.com>
Reviewed-by: Dmitry Osipenko <digetx@gmail.com>
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>