[FS#1424] usbmode sits in loop after install

[LEDE Bugs]

A new Flyspray task has been opened.  Details are below. 

User who did this - Sydney Meyer (sydney) 

Attached to Project - OpenWrt/LEDE Project
Summary - usbmode sits in loop after install
Task Type - Bug Report
Category - Base system
Status - Unconfirmed
Assigned To - 
Operating System - All
Severity - Low
Priority - Very Low
Reported Version - Trunk
Due in Version - Undecided
Due Date - Undecided
Details - - Name the tree/revision/version

OpenWrt Snapshot r6397-7cc9914

- Name the affected device

Huawei ME909s-120 LTE Card (12d1:15c1) on a PC Engines APU2 (amd64) in MBIM Mode.

- What does it do that it should not do / what does it not do that it should do

usbmode sits in a loop right after installation, doesn't switch the Modem in MBMI mode and thus no /dev/cdc-wdm0 device is created and prints constantly:

[   59.838090] usb 1-1.3: usbfs: process 6946 (usbmode) did not claim interface 1 before use
[   60.048534] usb 1-1.3: usbfs: interface 1 claimed by usbfs while 'usbmode' sets config #0
[   60.131996] usb 1-1.3: usbfs: process 7032 (usbmode) did not claim interface 1 before use
[   60.342459] usb 1-1.3: usbfs: interface 1 claimed by usbfs while 'usbmode' sets config #0

- Steps to reproduce

Install usb-modeswitch on OpenWrt Snapshot r6397-7cc9914

- What you have already done to workaround/fix the problem

Tried LEDE 17.01.4 r3560-79f57e422d without success, but messages are only printed once after "usbmode -s" is called, also there isn't a cdc-wdm0 device created. 

- Any additional info you thinks is important

This HW config is working fine with cdc_mbim on Debian with a 4.9 Kernel and their usb-modeswitch implementation.

More information can be found at the following URL:
https://bugs.openwrt.org/index.php?do=details&task_id=1424