[S390] Get rid of a lot of sparse warnings.

Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
diff --git a/arch/s390/kernel/crash.c b/arch/s390/kernel/crash.c
index 926ccee..8cc7c9f 100644
--- a/arch/s390/kernel/crash.c
+++ b/arch/s390/kernel/crash.c
@@ -9,6 +9,7 @@
 
 #include <linux/threads.h>
 #include <linux/kexec.h>
+#include <linux/reboot.h>
 
 void machine_crash_shutdown(struct pt_regs *regs)
 {