Remove unnecessary usbnet function in MTP+ADB mode.

With usbnet included in the current configuration, causing ADB not functioning.
On windows system, a device (usbnet) detected with no driver provided by Motorola.
Removing usbnet make MTP+ADB mode working normally.

Change-Id: Ifab1650aee512949a1943de9e55496855f699260
Merge "Remove unnecessary usbnet function in MTP+ADB mode." into kitkat