usb: gadget: f_gsi: Add support for super speed function suspend

Register gsi function suspend callback with composite device to
handle super speed function suspend and resume. Also, move
function suspend option masks to composite device layer.

Change-Id: Ie316973d855612ddc5440934344d18b04d49c567
Signed-off-by: Hemant Kumar <hemantk@codeaurora.org>