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.h b/drivers/usb/gadget/uvc.h
index 0a705e6..e92454c 100644
--- a/drivers/usb/gadget/uvc.h
+++ b/drivers/usb/gadget/uvc.h
@@ -107,11 +107,11 @@
 #define UVC_WARN_MINMAX				0
 #define UVC_WARN_PROBE_DEF			1
 
-extern unsigned int uvc_trace_param;
+extern unsigned int uvc_gadget_trace_param;
 
 #define uvc_trace(flag, msg...) \
 	do { \
-		if (uvc_trace_param & flag) \
+		if (uvc_gadget_trace_param & flag) \
 			printk(KERN_DEBUG "uvcvideo: " msg); \
 	} while (0)
 
@@ -220,16 +220,10 @@
 #define to_uvc_file_handle(handle) \
 	container_of(handle, struct uvc_file_handle, vfh)
 
-extern struct v4l2_file_operations uvc_v4l2_fops;
-
 /* ------------------------------------------------------------------------
  * Functions
  */
 
-extern int uvc_video_enable(struct uvc_video *video, int enable);
-extern int uvc_video_init(struct uvc_video *video);
-extern int uvc_video_pump(struct uvc_video *video);
-
 extern void uvc_endpoint_stream(struct uvc_device *dev);
 
 extern void uvc_function_connect(struct uvc_device *uvc);