Allow to use ncm function for usb tethering

Adding the configuration to decide using rndis or ncm for usb tethering.
If ncm is configured for TETHEIRNG_USB, then TETHERING_NCM is not
available.

Bug: 162920185
Test: atest TetheringTests
      manul testing usb tethering
Original-Change: https://android-review.googlesource.com/1730541
Merged-In: Ifc7eee2457a950a0e2d1c3cc89a3373a7ad23c9c
Change-Id: Ifc7eee2457a950a0e2d1c3cc89a3373a7ad23c9c
8 files changed