Use true instead of 1 in while

This resolves MISRA defects such as:

    plat/common/plat_bl1_common.c:63:[MISRA C-2012 Rule 14.4 (required)]
    The condition expression "1" does not have an essentially boolean type.

Change-Id: I679411980ad661191fbc834a44a5eca5494fd0e2
Signed-off-by: Jimmy Brisson <jimmy.brisson@arm.com>
diff --git a/plat/arm/board/sgi575/sgi575_err.c b/plat/arm/board/sgi575/sgi575_err.c
index c1cc1a7..21bfcb7 100644
--- a/plat/arm/board/sgi575/sgi575_err.c
+++ b/plat/arm/board/sgi575/sgi575_err.c
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2019, Arm Limited. All rights reserved.
+ * Copyright (c) 2019-2020, Arm Limited. All rights reserved.
  *
  * SPDX-License-Identifier: BSD-3-Clause
  */
@@ -11,7 +11,7 @@
  */
 void __dead2 plat_arm_error_handler(int err)
 {
-	while (1) {
+	while (true) {
 		wfi();
 	}
 }