media: ddbridge: return stv09xx id in port_has_stv0900_aa()

The returned value is required for further evaluation of the exact
demodulator chip (stv090x or stv0910).

Signed-off-by: Daniel Scheller <d.scheller@gmx.net>
Tested-by: Richard Scobie <r.scobie@clear.net.nz>
Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>