board: freescale: t208xrdb: fdt fixups under DM_ETH

Disable the FMan mEMAC 5 and 6 nodes from the fdt since they are not
available under the supported RCW. Also disable the associated
"fsl,dpa-ethernet" nodes that reference them.

This is a simplified version of the fdt_fixup_fman_ethernet call for
use under DM_ETH.

Signed-off-by: Camelia Groza <camelia.groza@nxp.com>
Reviewed-by: Priyanka Jain <priyanka.jain@nxp.com>
diff --git a/board/freescale/t208xrdb/t208xrdb.h b/board/freescale/t208xrdb/t208xrdb.h
index 22a496f..cd0a9f4 100644
--- a/board/freescale/t208xrdb/t208xrdb.h
+++ b/board/freescale/t208xrdb/t208xrdb.h
@@ -1,6 +1,7 @@
 /* SPDX-License-Identifier: GPL-2.0+ */
 /*
  * Copyright 2014 Freescale Semiconductor, Inc.
+ * Copyright 2021 NXP
  */
 
 #ifndef __CORENET_DS_H__
@@ -8,5 +9,6 @@
 
 void fdt_fixup_board_enet(void *blob);
 void pci_of_setup(void *blob, struct bd_info *bd);
+void fdt_fixup_board_fman_ethernet(void *blob);
 
 #endif