Use correct type when reading SCR register

The Secure Configuration Register is 64-bits in AArch64 and 32-bits in
AArch32. Use u_register_t instead of unsigned int to reflect this.

Change-Id: I51b69467baba36bf0cfaec2595dc8837b1566934
Signed-off-by: Louis Mayencourt <louis.mayencourt@arm.com>
diff --git a/plat/mediatek/mt8183/plat_pm.c b/plat/mediatek/mt8183/plat_pm.c
index 2358ec6..6094a17 100644
--- a/plat/mediatek/mt8183/plat_pm.c
+++ b/plat/mediatek/mt8183/plat_pm.c
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2019, MediaTek Inc. All rights reserved.
+ * Copyright (c) 2019-2020, MediaTek Inc. All rights reserved.
  *
  * SPDX-License-Identifier: BSD-3-Clause
  */
@@ -197,7 +197,7 @@
 
 static void plat_cpu_standby(plat_local_state_t cpu_state)
 {
-	unsigned int scr;
+	u_register_t scr;
 
 	scr = read_scr_el3();
 	write_scr_el3(scr | SCR_IRQ_BIT | SCR_FIQ_BIT);