V4L/DVB (10378): gspca - main: Avoid error on set interface on disconnection.

Signed-off-by: NJean-Francois Moine <moinejf@free.fr>
Signed-off-by: NMauro Carvalho Chehab <mchehab@redhat.com>

drivers/media/video/gspca/gspca.c

@@ -666,7 +666,8 @@ static void gspca_stream_off(struct gspca_dev *gspca_dev)
 	    && gspca_dev->sd_desc->stopN)
 		gspca_dev->sd_desc->stopN(gspca_dev);
 	destroy_urbs(gspca_dev);
-	gspca_set_alt0(gspca_dev);
+	if (gspca_dev->present)
+		gspca_set_alt0(gspca_dev);
 	if (gspca_dev->sd_desc->stop0)
 		gspca_dev->sd_desc->stop0(gspca_dev);
 	PDEBUG(D_STREAM, "stream off OK");