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/arm/common/arm_common.c b/plat/arm/common/arm_common.c
index 03d842a..255e6b4 100644
--- a/plat/arm/common/arm_common.c
+++ b/plat/arm/common/arm_common.c
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2015-2019, ARM Limited and Contributors. All rights reserved.
+ * Copyright (c) 2015-2020, ARM Limited and Contributors. All rights reserved.
  *
  * SPDX-License-Identifier: BSD-3-Clause
  */
@@ -173,7 +173,7 @@
 int plat_sdei_validate_entry_point(uintptr_t ep, unsigned int client_mode)
 {
 	uint64_t par, pa;
-	uint32_t scr_el3;
+	u_register_t scr_el3;
 
 	/* Doing Non-secure address translation requires SCR_EL3.NS set */
 	scr_el3 = read_scr_el3();