[media] pvrusb2: fix sparse warning

drivers/media/usb/pvrusb2/pvrusb2-hdw.c:2871:13: warning: symbol 'pvr2_hdw_get_detected_std' was not declared. Should it be static?
Signed-off-by: Hans Verkuil <hans.verkuil@cisco.com>
Acked-by: Mike Isely <isely@pobox.com>
Signed-off-by: Mauro Carvalho Chehab <m.chehab@samsung.com>

drivers/media/usb/pvrusb2/pvrusb2-hdw.c

@@ -2868,7 +2868,7 @@ static void pvr2_subdev_set_control(struct pvr2_hdw *hdw, int id,
 		pvr2_subdev_set_control(hdw, id, #lab, (hdw)->lab##_val); \
 	}
 
-v4l2_std_id pvr2_hdw_get_detected_std(struct pvr2_hdw *hdw)
+static v4l2_std_id pvr2_hdw_get_detected_std(struct pvr2_hdw *hdw)
 {
 	v4l2_std_id std;
 	std = (v4l2_std_id)hdw->std_mask_avail;