p1_p2_rdb: Don't compile board_eth_init() for DM_ETH

The board_eth_init() is only used by legacy ethernet driver framework,
so do not compile it when DM_ETH config has been selected.

Signed-off-by: Hou Zhiqiang <Zhiqiang.Hou@nxp.com>
Reviewed-by: Vladimir Oltean <vladimir.oltean@nxp.com>
[Rebased]
Signed-off-by: Priyanka Jain <priyanka.jain@nxp.com>

board/freescale/p1_p2_rdb_pc/p1_p2_rdb_pc.c

@@ -359,6 +359,7 @@ int board_early_init_r(void)
 	return 0;
 }
 
+#ifndef CONFIG_DM_ETH
 int board_eth_init(struct bd_info *bis)
 {
 	struct fsl_pq_mdio_info mdio_info;
@@ -406,6 +407,7 @@ int board_eth_init(struct bd_info *bis)
 
 	return pci_eth_init(bis);
 }
+#endif
 
 #if defined(CONFIG_QE) && \
 	(defined(CONFIG_TARGET_P1025RDB) || defined(CONFIG_TARGET_P1021RDB))