IB/mlx4: Fix device managed flow steering support test

Perform the test for device managed flow steering support even if
memory windows are not supported. I noticed this because smatch
reported inconsistent indentation for the device managed flow
steering support test.

Signed-off-by: Bart Van Assche <bart.vanassche@sandisk.com>
Reviewed-by: Sagi Grimberg <sagi@grimberg.me>
Cc: Yishai Hadas <yishaih@mellanox.com>
Reviewed-by: Leon Romanovsky <leonro@mellanox.com>
Signed-off-by: Doug Ledford <dledford@redhat.com>