pass required OIDs as function parameter

And forget about any model definition at the same time
make the function more versatile

So as to be handle either dot1dTpFdbPort or dot1qTpFdpPort values
use dot1qTpFdbPort for additional mac addresses

dot1dTpFdbPort enumerates mac addresses seen on default vlan, while
dot1qTpFdbPort enumerates mac addresses seen on other vlans.
On every device, we use the first one as usual, and then we try the
second one. If no results are found, we fallback on what seems to be
cisco-specific vlan context method.