The flushing of the Tx hardware queues is only supported at a certain
level of the hardware.  Retrieve the current version of the hardware
and use that to determine if flushing is supported.
Signed-off-by: NTom Lendacky <thomas.lendacky@amd.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>