board: vexpress64: enable bloblist for SPL handoff

Enable bloblist on vexpress64 platforms to facilitate information
passing from TF-A using the firmware handoff framework.

Signed-off-by: Harrison Mutai <harrison.mutai@arm.com>
diff --git a/board/armltd/vexpress64/vexpress64.c b/board/armltd/vexpress64/vexpress64.c
index b5ede58..0b75c13 100644
--- a/board/armltd/vexpress64/vexpress64.c
+++ b/board/armltd/vexpress64/vexpress64.c
@@ -100,7 +100,9 @@
  * Push the variable into the .data section so that it
  * does not get cleared later.
  */
+#ifdef CONFIG_OF_HAS_PRIOR_STAGE
 unsigned long __section(".data") prior_stage_fdt_address[2];
+#endif
 
 #ifdef CONFIG_OF_BOARD
 
@@ -151,6 +153,7 @@
 }
 #endif
 
+#ifdef CONFIG_OF_HAS_PRIOR_STAGE
 /*
  * Filter for a valid DTB, as TF-A happens to provide a pointer to some
  * data structure using the DTB format, which we cannot use.
@@ -201,6 +204,7 @@
 	return -ENXIO;
 }
 #endif
+#endif
 
 /* Actual reset is done via PSCI. */
 void reset_cpu(void)