V4L/DVB (9577): saa7134-dvb: MFE attachment clean-up for saa-7134 dvb

This cleans-up MFE attachment for saa-7134 dvb
devices.

note: MFE is not fully implemented here yet.

Signed-off-by: Darron Broad <darron@kewl.org>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>