configs: sama5d2_ptc_ek: 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/sama5d2_ptc_ek_nandflash_defconfig b/configs/sama5d2_ptc_ek_nandflash_defconfig
index 1b3d097..4e39406 100644
--- a/configs/sama5d2_ptc_ek_nandflash_defconfig
+++ b/configs/sama5d2_ptc_ek_nandflash_defconfig
@@ -66,3 +66,4 @@
 CONFIG_W1_GPIO=y
 CONFIG_W1_EEPROM=y
 CONFIG_W1_EEPROM_DS24XXX=y
+CONFIG_OF_LIBFDT_OVERLAY=y