[media] pt3: fix device identification

As warned by smatch:
	drivers/media/pci/pt3/pt3.c:398 pt3_attach_fe() error: strncmp() '"tc90522sat"' too small (11 vs 20)

Clearly, the logic is doing the wrong thing, as it is not comparing the strings
on the right way.

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