net: qmi_wwan: interface #11 in Sierra Wireless MC73xx is not QMI

This interface is unusable, as the cdc-wdm character device doesn't reply to
any QMI command. Also, the out-of-tree Sierra Wireless GobiNet driver fully
skips it.

Signed-off-by: Aleksander Morgado <aleksander@aleksander.es>
Acked-by: Bjørn Mork <bjorn@mork.no>
Signed-off-by: David S. Miller <davem@davemloft.net>