V4L/DVB: uvc: Fix multiple symbols definitions with UVC gadget and host drivers

The UVC gadget driver borrowed code from the UVC host driver without
changing the symbol names. This results in a namespace clash with
multiple definitions of several symbols when compiling both drivers in
the kernel.

Make all generic UVC functions and variables static in the UVC gadget
driver, as the symbols are not referenced outside of the gadget driver.
Rename the uvc_trace_param global variable to uvc_gadget_trace_param.

Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>
diff --git a/drivers/usb/gadget/uvc_video.c b/drivers/usb/gadget/uvc_video.c
index de8cbc4..b08f354 100644
--- a/drivers/usb/gadget/uvc_video.c
+++ b/drivers/usb/gadget/uvc_video.c
@@ -271,7 +271,7 @@
  * This function fills the available USB requests (listed in req_free) with
  * video data from the queued buffers.
  */
-int
+static int
 uvc_video_pump(struct uvc_video *video)
 {
 	struct usb_request *req;
@@ -328,7 +328,7 @@
 /*
  * Enable or disable the video stream.
  */
-int
+static int
 uvc_video_enable(struct uvc_video *video, int enable)
 {
 	unsigned int i;
@@ -367,7 +367,7 @@
 /*
  * Initialize the UVC video stream.
  */
-int
+static int
 uvc_video_init(struct uvc_video *video)
 {
 	INIT_LIST_HEAD(&video->req_free);