If you stop then start a port that had already sent some packets,
there was a segfault due to not resetting the number of completed
sends to zero.
Fixes: a3b1e9551c26 ("net/enic: streamline mbuf handling in Tx path")
Signed-off-by: Nelson Escobar <neescoba@cisco.com>
Reviewed-by: John Daley <johndale@cisco.com>