fix: remove old-style declarations

TF-A wants to eventually enable -Wold-style-definition globally. Convert
the rare few instances where this is still the case.

Signed-off-by: Boyan Karatotev <boyan.karatotev@arm.com>
Change-Id: I9c450fc875cf097e6de2ed577ea3b085821c9f5e
diff --git a/plat/xilinx/zynqmp/zynqmp_ipi.c b/plat/xilinx/zynqmp/zynqmp_ipi.c
index 4ea3c6a..acd31df 100644
--- a/plat/xilinx/zynqmp/zynqmp_ipi.c
+++ b/plat/xilinx/zynqmp/zynqmp_ipi.c
@@ -21,7 +21,7 @@
 #include <plat_private.h>
 
 /* Zynqmp ipi configuration table */
-const static struct ipi_config zynqmp_ipi_table[] = {
+static const struct ipi_config zynqmp_ipi_table[] = {
 	/* APU IPI */
 	{
 		.ipi_bit_mask = 0x1,