vcs: invoke the vt update callback when /dev/vcs* is written to

A notifier chain is called whenever the vt code modifies a terminal
content, except for one case which is when the modification comes
through writes to /dev/vcs* devices. Let's add the missing notifier
invocation at the end of vcs_write() for that case too.

Signed-off-by: Nicolas Pitre <[e-mail]>
Cc: Alan Cox <[e-mail]>
Signed-off-by: Greg Kroah-Hartman <[e-mail]>

drivers/char/vc_screen.c

···
 	}
 	*ppos += written;
 	ret = written;
+	if (written)
+		vcs_scr_updated(vc);
 
 unlock_out:
 	release_console_sem();

drivers/char/vt.c

···
 	}
 }
 
+void vcs_scr_updated(struct vc_data *vc)
+{
+	notify_update(vc);
+}
+
 /*
  *	Visible symbols for modules
  */

include/linux/selection.h

···
 
 extern u16 vcs_scr_readw(struct vc_data *vc, const u16 *org);
 extern void vcs_scr_writew(struct vc_data *vc, u16 val, u16 *org);
+extern void vcs_scr_updated(struct vc_data *vc);
 
 #endif