V4L/DVB (8380): saa7115: use saa7115_auto instead of saa711x as the autodetect driver name.

Having an _auto suffix is less ambiguous than a 'saa711x' identifier.
It's also used like this in the saa7127 driver.

Thanks to Jean Delvare for suggesting this.

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