When invalid keyword is specified, ifconfig(8) is silent about it, instead random request is sent to the driver.
Before the patch:
`
root@r-freeb43:~ # ifconfig mce0 mediaopt -txpause,-rxpause
ifconfig: SIOCSIFMEDIA (media): Device not configured
`
After:
`
root@r-freeb43:~ # ifconfig mce0 mediaopt -txpause,-rxpause
ifconfig: unknown option: -txpause
`