[media] xirlink_cit: comment unreachable code

drivers/media/usb/gspca/xirlink_cit.c:1776 cit_start_model2() info: ignoring unreachable code.
drivers/media/usb/gspca/xirlink_cit.c:1858 cit_start_model2() info: ignoring unreachable code.
drivers/media/usb/gspca/xirlink_cit.c:1910 cit_start_model2() info: ignoring unreachable code.

Signed-off-by: Mauro Carvalho Chehab <mchehab@osg.samsung.com>