iwlegacy: more priv->mutex serialization

Check status bits with mutex taken, because when we wait for mutex
unlock, status can change. Patch should also make remaining sync
commands be send with priv->mutex taken. That will prevent execute
these commands when we are currently reset firmware, what could
possibly cause troubles.

Signed-off-by: Stanislaw Gruszka <sgruszka@redhat.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>