[media] saa7115: add detection code for gm7113c

Adds a code that (auto)detects gm7113c clones. The auto-detection
here is not perfect, as, on contrary to what it would be expected
by looking into its datasheets some devices would return, instead:
	saa7115 0-0025: chip 10 10 10 10 10 10 10 10 10 10 10 10 10 10 10 10 @ 0x4a is unknown
(found on a device labeled as GM7113C 1145 by Ezequiel Garcia)

Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>
Tested-by: Jon Arne Jørgensen <jonarne@jonarne.no>
Tested-by: Ezequiel Garcia <ezequiel.garcia@free-electrons.com>
Signed-off-by: Hans Verkuil <hans.verkuil@cisco.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>