[S390] sparse: fix sparse warnings with __user pointers

Use __force to quiet sparse warnings about user address space.

Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
diff --git a/arch/s390/kernel/traps.c b/arch/s390/kernel/traps.c
index 79eee3f..a9807dd 100644
--- a/arch/s390/kernel/traps.c
+++ b/arch/s390/kernel/traps.c
@@ -334,7 +334,8 @@
 	info.si_signo = SIGTRAP;
 	info.si_errno = 0;
 	info.si_code = TRAP_HWBKPT;
-	info.si_addr = (void *) current->thread.per_event.address;
+	info.si_addr =
+		(void __force __user *) current->thread.per_event.address;
 	force_sig_info(SIGTRAP, &info, current);
 }