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/common/plat_bl1_common.c b/plat/common/plat_bl1_common.c
index d29a27f..1c6d68b 100644
--- a/plat/common/plat_bl1_common.c
+++ b/plat/common/plat_bl1_common.c
@@ -60,7 +60,7 @@
 
 __dead2 void bl1_plat_fwu_done(void *client_cookie, void *reserved)
 {
-	while (1)
+	while (true)
 		wfi();
 }