[media] em28xx: extract the device configuration dataset from eeproms with 16 bit address width

The new eeproms with 16 address width still have the the device config dataset
(the content of the old 8 bit eeproms) embedded.
Hauppauge also continues to include the tveeprom data structure inside this
dataset in their devices.
The start address of the dataset depends on the start address of the microcode
and a variable additional offset.
It should be mentioned that Camera devices seem to use a different dataset type,
which is not yet supported.
Tested with devices "Hauppauge HVR-930C". I've also checked the USB-log from the
"MSI Digivox ATSC" and it works the same way.

Signed-off-by: Frank Schäfer <fschaefer.oss@googlemail.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>