[media] saa7134: fix detection of external decoders

As warned by smatch:
	drivers/media/pci/saa7134/saa7134-core.c:840 saa7134_create_entities() info: ignoring unreachable code.
	drivers/media/pci/saa7134/saa7134-core.c:843 saa7134_create_entities() warn: curly braces intended?

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