[media] ivtv: avoid going past input/audio array

As reported by smatch:
	drivers/media/pci/ivtv/ivtv-driver.c:832 ivtv_init_struct2() error: buffer overflow 'itv->card->video_inputs' 6 <= 6

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