tty: vt, fix bogus division in csi_J

BugLink: http://bugs.launchpad.net/bugs/1642572

commit 42acfc66 upstream.

In csi_J(3), the third parameter of scr_memsetw (vc_screenbuf_size) is
divided by 2 inappropriatelly. But scr_memsetw expects size, not
count, because it divides the size by 2 on its own before doing actual
memset-by-words.

So remove the bogus division.
Signed-off-by: Jiri Slaby <jslaby@suse.cz>
Cc: Petr Písař <ppisar@redhat.com>
Fixes: f8df13e0 (tty: Clean console safely)
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Luis Henriques <luis.henriques@canonical.com>

drivers/tty/vt/vt.c

@@ -1189,7 +1189,7 @@ static void csi_J(struct vc_data *vc, int vpar)
 			break;
 		case 3: /* erase scroll-back buffer (and whole display) */
 			scr_memsetw(vc->vc_screenbuf, vc->vc_video_erase_char,
-				    vc->vc_screenbuf_size >> 1);
+				    vc->vc_screenbuf_size);
 			set_origin(vc);
 			if (CON_IS_VISIBLE(vc))
 				update_screen(vc);