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/imx/imx8qx/imx8qx_psci.c b/plat/imx/imx8qx/imx8qx_psci.c
index aab3a2d..5f05566 100644
--- a/plat/imx/imx8qx/imx8qx_psci.c
+++ b/plat/imx/imx8qx/imx8qx_psci.c
@@ -18,7 +18,7 @@
 
 #include "../../common/sci/imx8_mu.h"
 
-const static int ap_core_index[PLATFORM_CORE_COUNT] = {
+static const int ap_core_index[PLATFORM_CORE_COUNT] = {
 	SC_R_A35_0, SC_R_A35_1, SC_R_A35_2, SC_R_A35_3
 };