net: qrtr: Add support for USB transport

Add support for USB transport for QRTR. This transport driver
exposes two bulk endpoints and registers tx and rx functions
with qrtr framework for transport of IPC messages to and from
connected device.

Change-Id: Id3f2b5bf3569cfa933edef40bcf13157ff3e2f56
Signed-off-by: Gustavo Solaira <gustavos@codeaurora.org>
Signed-off-by: Ajay Agarwal <ajaya@codeaurora.org>
Signed-off-by: Chris Lew <clew@codeaurora.org>