[media] cx231xx-avcore: get rid of a sophisticated do-nothing code

drivers/media/usb/cx231xx/cx231xx-avcore.c: In function 'cx231xx_capture_start':
drivers/media/usb/cx231xx/cx231xx-avcore.c:2637:3: warning: suggest braces around empty body in an 'else' statement [-Wempty-body]

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