qcserial: bind to DM/DIAG port on Gobi 1K devices

Turns out we just need altsetting 1 and then we can talk to it.

Signed-off-by: Dan Williams <dcbw@redhat.com>
Cc: stable <stable@vger.kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>