net/mlx4_en: Fix resource leak in error flow

Wrong condition was used when calling iounmap.

Signed-off-by: Dotan Barak <dotanb@dev.mellanox.com>
Signed-off-by: Amir Vadai <amirv@mellanox.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
1 file changed