configs: sama5d4_xplained: add fdt overlay support

Add commands for fdt overlay merging. This is required for the boot scripts
that detect PDAs and apply specific overlays to the DTB passed on to kernel.

Signed-off-by: Eugen Hristev <eugen.hristev@microchip.com>
diff --git a/configs/sama5d4_xplained_mmc_defconfig b/configs/sama5d4_xplained_mmc_defconfig
index 26960eb..f60b6b5 100644
--- a/configs/sama5d4_xplained_mmc_defconfig
+++ b/configs/sama5d4_xplained_mmc_defconfig
@@ -88,3 +88,4 @@
 CONFIG_W1_GPIO=y
 CONFIG_W1_EEPROM=y
 CONFIG_W1_EEPROM_DS24XXX=y
+CONFIG_OF_LIBFDT_OVERLAY=y
diff --git a/configs/sama5d4_xplained_nandflash_defconfig b/configs/sama5d4_xplained_nandflash_defconfig
index c463c74..3524dbf 100644
--- a/configs/sama5d4_xplained_nandflash_defconfig
+++ b/configs/sama5d4_xplained_nandflash_defconfig
@@ -84,3 +84,4 @@
 CONFIG_W1_GPIO=y
 CONFIG_W1_EEPROM=y
 CONFIG_W1_EEPROM_DS24XXX=y
+CONFIG_OF_LIBFDT_OVERLAY=y
diff --git a/configs/sama5d4_xplained_spiflash_defconfig b/configs/sama5d4_xplained_spiflash_defconfig
index 13869da..3f519cd 100644
--- a/configs/sama5d4_xplained_spiflash_defconfig
+++ b/configs/sama5d4_xplained_spiflash_defconfig
@@ -88,3 +88,4 @@
 CONFIG_W1_GPIO=y
 CONFIG_W1_EEPROM=y
 CONFIG_W1_EEPROM_DS24XXX=y
+CONFIG_OF_LIBFDT_OVERLAY=y