fix(xilinx): add headers to resolve compile time issue

Add common/debug.h and libfdt.h files to the common file
for XILINX_OF_BOARD_DTB_ADDR configuration.

Signed-off-by: Akshay Belsare <akshay.belsare@amd.com>
Change-Id: I577cc018eda34e186e48594a62c54eb55f11bbd3

plat/xilinx/common/plat_fdt.c

@@ -4,8 +4,10 @@
  * SPDX-License-Identifier: BSD-3-Clause
  *
  */
+#include <common/debug.h>
 #include <common/fdt_fixup.h>
 #include <common/fdt_wrappers.h>
+#include <libfdt.h>
 
 #include <plat_fdt.h>
 #include <platform_def.h>