fix(versal): add external declaration

This corrects the MISRA violation C2012-8.4:
A compatible declaration shall be visible when an object or
function with external linkage is defined.

Change-Id: I91817596c5de84b259a5dffcc01a7b1106a5b7a4
Signed-off-by: Maheedhar Bollapalli <maheedharsai.bollapalli@amd.com>
diff --git a/plat/xilinx/common/versal.c b/plat/xilinx/common/versal.c
index 3ea022c..b37dc76 100644
--- a/plat/xilinx/common/versal.c
+++ b/plat/xilinx/common/versal.c
@@ -7,6 +7,7 @@
 #include <common/debug.h>
 #include <lib/mmio.h>
 #include <lib/smccc.h>
+#include <plat/common/platform.h>
 #include <services/arm_arch_svc.h>
 
 #include <plat_private.h>