V4L/DVB (11838): uvcvideo: Add Lenovo Thinkpad SL400 to device list comments

Update the 17ef:480b device comment to list Lenovo Thinkpad SL400.

Signed-off-by: Filipe Rosset <rosset.filipe@gmail.com>
Signed-off-by: Laurent Pinchart <laurent.pinchart@skynet.be>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>