Only try to use the 82503 serial interface for the 82557 chipsets.  The datasheet says it is only valid for such chipsets and shouldn't be used with others.  This fixes some 82559 based cards which otherwise only work at 10Mbit.
Only try to use the 82503 serial interface for the 82557 chipsets.  The
datasheet says it is only valid for such chipsets and shouldn't be used
with others.  This fixes some 82559 based cards which otherwise only
work at 10Mbit.

MFC after:	5 days
Tested by:	krion

jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase