V4L/DVB (8379): saa7127: Make device detection optional

The saa7127 driver supports all of SAA7126, SAA7127, SAA7128 and
SAA1729 devices. Declare all these devices, so that board drivers can
tell which device is present, instead of always relying on
auto-detection (which needs to write to the chip, eek!).

We still need the detection for ivtv, so a special device name
"saa7127_auto" can be used when the caller doesn't know exactly which
device is present.

Signed-off-by: Jean Delvare <khali@linux-fr.org>
Signed-off-by: Hans Verkuil <hverkuil@xs4all.nl>
Signed-off-by: Mauro Carvalho Chehab <mchehab@infradead.org>