usb: gadget: Add snapshot of USB RNDIS Function driver

This change adds USB RNDIS function driver which allows communication
between USB BAM and IPA BAM for tethering functionality over USB.

This snapshot is taken as of msm-4.4 'commit fa53f7f14b3c5f ("soc:
qcom: ipc_router_glink_xprt: Add rx intent timeout for glink")'.

This change adding changes to use cdev device instead of misc device
and also fixes different coding style related warnings.

Change-Id: Ic6925c579095dd853a8e165d809dfb7422365ed0
Signed-off-by: Chandana Kishori Chiluveru <cchiluve@codeaurora.org>