mhi_bus: dev: netdev: add network interface driver

MHI based net device driver is used for transferring IP
traffic between host and modem. Driver allows clients to
transfer data using standard network interface.

CRs-Fixed: 2204910
Change-Id: I47d43c63edb6ef2bd28d4c8c9692326195b4f9a4
Signed-off-by: Sujeev Dias <sdias@codeaurora.org>