usb4bsd: Fix if_urndis/umodem probing conflict.

Previously, if_urndis would not detect certain devices (among them
the HTC One) due to a conflict with certain USB modems from Huawei.

Fix this by making umodem check explicitly for Huawei as the vendor.

As far as I can see, devd(8) would now load both umodem.ko and
if_urndis.ko for these modems but only umodem.ko would attach, so
we should be fine.

However, so far only the urndis(4) part was actually tested.

Submitted-by:  Yellow Rabbit <yrabbit@sdf.lonestar.org>
Tested-by:     Robin Hahling <robin.hahling@gw-computing.net>
Dragonfly-bug: <https://bugs.dragonflybsd.org/issues/2725>
urndis.4: No ifmedia support in this driver.