usb: gadget: uvc: prepare the code for multi instance support

The following changes that are present in the downstream but not
in upstream kernel of v4.9 are reverted temporarily to bring in
the multi instance patches from the upstream without heavy
conflicts.

"usb: gadget: uvc: Update frame size as per frame type"
"usb: gadget: uvc: Missing files for configfs interface"
"usb: gadget: f_uvc: Fix incorrect frame indexing"
"usb: gadget: uvc: Add support for UVC 1.5"

Change-Id: I7cd94c457a7c242acaed895f9c0502e409f83d5b
Signed-off-by: Pavankumar Kondeti <pkondeti@codeaurora.org>