s390: Convert BUG() to use unreachable()

Use the new unreachable() macro instead of for(;;);

Signed-off-by: David Daney <ddaney@caviumnetworks.com>
Acked-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
CC: Heiko Carstens <heiko.carstens@de.ibm.com>
CC: linux390@de.ibm.com
CC: linux-s390@vger.kernel.org
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/arch/s390/include/asm/bug.h b/arch/s390/include/asm/bug.h
index 7efd0ab..efb74fd 100644
--- a/arch/s390/include/asm/bug.h
+++ b/arch/s390/include/asm/bug.h
@@ -49,7 +49,7 @@
 
 #define BUG() do {					\
 	__EMIT_BUG(0);					\
-	for (;;);					\
+	unreachable();					\
 } while (0)
 
 #define WARN_ON(x) ({					\