xilinx: zynq: Enable fdt apply utility for zynq

Enables the FDT library (libfdt) overlay support for zynq platforms
to be able to use fdt apply command.

Signed-off-by: Raju Kumar Pothuraju <rajukumar.pothuraju@amd.com>
Signed-off-by: Michal Simek <michal.simek@amd.com>
Link: https://lore.kernel.org/r/ab26dd186fb752b3d607e6160ae5baf6661d5de7.1688990179.git.michal.simek@amd.com
diff --git a/configs/xilinx_zynq_virt_defconfig b/configs/xilinx_zynq_virt_defconfig
index 474abc7..9900577 100644
--- a/configs/xilinx_zynq_virt_defconfig
+++ b/configs/xilinx_zynq_virt_defconfig
@@ -7,6 +7,7 @@
 CONFIG_ENV_OFFSET=0xE00000
 CONFIG_DM_GPIO=y
 CONFIG_DEFAULT_DEVICE_TREE="zynq-zc706"
+CONFIG_OF_LIBFDT_OVERLAY=y
 CONFIG_SPL_STACK_R_ADDR=0x200000
 CONFIG_SPL_STACK=0xfffffe00
 CONFIG_SPL=y