[S390] fix non-smp compile.

Fix compile of sclp_quiesce for CONFIG_SMP=n.

Signed-off-by: Jan Glauber <jan.glauber@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>

drivers/s390/char/sclp_quiesce.c

@@ -16,6 +16,7 @@
 #include <asm/atomic.h>
 #include <asm/ptrace.h>
 #include <asm/sigp.h>
+#include <asm/smp.h>
 
 #include "sclp.h"