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/juno/juno_bl1_setup.c b/plat/arm/board/juno/juno_bl1_setup.c
index 25a27da..2234055 100644
--- a/plat/arm/board/juno/juno_bl1_setup.c
+++ b/plat/arm/board/juno/juno_bl1_setup.c
@@ -97,7 +97,7 @@
 	/* Setup the watchdog to reset the system as soon as possible */
 	sp805_refresh(ARM_SP805_TWDG_BASE, 1U);
 
-	while (1)
+	while (true)
 		wfi();
 }