media: usbtv: Remove useless locks in usbtv_video_free()

[ Upstream commit 65e6a277 ]

Remove locks calls in usbtv_video_free() because
are useless and may led to a deadlock as reported here:
https://syzkaller.appspot.com/x/bisect.txt?x=166dc872180000


Also remove usbtv_stop() call since it will be called when
unregistering the device.

Before 'c838530d' this issue would only be noticed if you
disconnect while streaming and now it is noticeable even when
disconnecting while not streaming.

Fixes: c838530d ("media: media videobuf2: Be more flexible on the number of queue stored buffers")
Fixes: f3d27f34 ("[media] usbtv: Add driver for Fushicai USBTV007 video frame grabber")

Signed-off-by: Benjamin Gaignard <benjamin.gaignard@collabora.com>
Reviewed-by: Tomasz Figa <tfiga@chromium.org>
Tested-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
[hverkuil: fix minor spelling mistake in log message]
Signed-off-by: Sasha Levin <sashal@kernel.org>