OSD fixes.

menu.cpp

@@ -760,6 +760,7 @@ static void vga_nag()
 		OsdWrite(n++, "  or enable scaler on VGA:");
 		OsdWrite(n++, "       vga_scaler=1");
 		for (; n < OsdGetSize(); n++) OsdWrite(n);
+		OsdUpdate();
 		OsdEnable(0);
 		EnableOsd_on(OSD_HDMI);
 	}

osd.cpp

@@ -695,6 +695,9 @@ char* OsdCoreName()
 
 void OsdUpdate()
 {
+	// reset the output channel (workaround)
+	if(osdset) spi_osd_cmd(OSD_CMD_WRITE);
+
 	int n = is_menu_core() ? 19 : osd_size;
 	for (int i = 0; i < n; i++)
 	{