board: sama5d4_xplained: Set mac address from eeprom

Add the code to set the ethernet mac address from eeprom by using
the common code from the common folder.

Signed-off-by: Wenyou Yang <wenyou.yang@microchip.com>
Reviewed-by: Simon Glass <sjg@chromium.org>
diff --git a/include/configs/sama5d4_xplained.h b/include/configs/sama5d4_xplained.h
index c8462b0..08f8650 100644
--- a/include/configs/sama5d4_xplained.h
+++ b/include/configs/sama5d4_xplained.h
@@ -12,6 +12,8 @@
 
 #include "at91-sama5_common.h"
 
+#define CONFIG_MISC_INIT_R
+
 /* SDRAM */
 #define CONFIG_NR_DRAM_BANKS		1
 #define CONFIG_SYS_SDRAM_BASE           ATMEL_BASE_DDRCS