usb: Add network bridge host driver for dun and rmnet

This host driver will be used to communicate with modem devices
with dial up network and RMNET interfaces. This driver works as
a bridge to pass control and data packets between the modem and
peripheral usb gadget driver. Driver currently supports
modem devices (vendor ID 0x05c6) with PIDs 0x9001

Change-Id: Id85b552b39d061528a1c3c90a354d73580c9b631
Signed-off-by: Hemant Kumar <hemantk@codeaurora.org>
Signed-off-by: Jack Pham <jackp@codeaurora.org>