vt: remove lines parameter from scrollback

It is always called with 0, so remove the parameter and pass the
default down to scrolldelta without checking.

Signed-off-by: Jiri Slaby <jslaby@suse.cz>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
diff --git a/drivers/tty/vt/vt.c b/drivers/tty/vt/vt.c
index dc12532..abc79ae1 100644
--- a/drivers/tty/vt/vt.c
+++ b/drivers/tty/vt/vt.c
@@ -1102,11 +1102,9 @@
 	gotoxy(vc, new_x, vc->vc_decom ? (vc->vc_top + new_y) : new_y);
 }
 
-void scrollback(struct vc_data *vc, int lines)
+void scrollback(struct vc_data *vc)
 {
-	if (!lines)
-		lines = vc->vc_rows / 2;
-	scrolldelta(-lines);
+	scrolldelta(-(vc->vc_rows / 2));
 }
 
 void scrollfront(struct vc_data *vc, int lines)