media: dw2102: probe for demodulator i2c address

This is required to support the Terratec S2 USB Box Revision 4, which
reused usb vid:pid, but has a different demodulator (m88ds3103b) at
i2c address 0x6a.

[fixed checkpatch issues]

Signed-off-by: Michael Bunk <micha@freedict.org>
Signed-off-by: Brad Love <brad@nextdimension.cc>
Signed-off-by: Sean Young <sean@mess.org>
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>