usb: gadget: Add support for RmNet CV2X instance

Add support for RmNet CV2X interface. Details of the patch:
 - Add support for 2 normal EPs to be used in GSI mode
 - Add new protocol ID and make necessary changes

For this new protocol USB_PROT_RMNET_V2X_IPA:
 - Use USB2_PROD and USB2_CONS as channel client type
 - Use normal EPs
 - Pass dummy GEVENTCOUNT register address to GSI.

Change-Id: I35e7f4f52562cd4fa8ffab4e2950c17827c2cc4f
Signed-off-by: Ajay Agarwal <ajaya@codeaurora.org>