usb: f_gsi: Add generic function driver for GSI transport

Adds a generic function driver that will handle all functions
that support h/w acceleration to IPA over GSI.
This function driver leverages common data path and implements
protocol specific control path.

Change-Id: I414478c76d950a568155ac8b0c2d180170cf7183
Signed-off-by: Devdutt Patnaik <dpatnaik@codeaurora.org>
Signed-off-by: Hemant Kumar <hemantk@codeaurora.org>