usb: gadget: function: uvc_v4l2.c: fix sparse warnings

this patch fixes following sparse warnings:

uvc_v4l2.c:264:29: warning: symbol 'uvc_v4l2_ioctl_ops' was not declared. Should it be static?
uvc_v4l2.c:355:29: warning: symbol 'uvc_v4l2_fops' was not declared. Should it be static?

Acked-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: Lad, Prabhakar <prabhakar.csengg@gmail.com>
Signed-off-by: Felipe Balbi <balbi@ti.com>