sfxge: Fix if_baudrate reports
sfxge: Fix if_baudrate reports

This field is supposed to be set to the interface bit rate, but for some
reason I thought it was denominated in kilobits.  Multiply the values up
accordingly, taking care to saturate rather than overflow on 32-bit
architectures.

Submitted by:	Ben Hutchings <bwh -at- solarflare.com>
MFC after:	3 weeks

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