[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/lib/uaccess_pt.c b/arch/s390/lib/uaccess_pt.c
index 7483383..342ae35 100644
--- a/arch/s390/lib/uaccess_pt.c
+++ b/arch/s390/lib/uaccess_pt.c
@@ -342,7 +342,8 @@
 	if (segment_eq(get_fs(), KERNEL_DS))
 		return __futex_atomic_op_pt(op, uaddr, oparg, old);
 	spin_lock(&current->mm->page_table_lock);
-	uaddr = (int __user *) __dat_user_addr((unsigned long) uaddr);
+	uaddr = (u32 __force __user *)
+		__dat_user_addr((__force unsigned long) uaddr);
 	if (!uaddr) {
 		spin_unlock(&current->mm->page_table_lock);
 		return -EFAULT;
@@ -378,7 +379,8 @@
 	if (segment_eq(get_fs(), KERNEL_DS))
 		return __futex_atomic_cmpxchg_pt(uval, uaddr, oldval, newval);
 	spin_lock(&current->mm->page_table_lock);
-	uaddr = (int __user *) __dat_user_addr((unsigned long) uaddr);
+	uaddr = (u32 __force __user *)
+		__dat_user_addr((__force unsigned long) uaddr);
 	if (!uaddr) {
 		spin_unlock(&current->mm->page_table_lock);
 		return -EFAULT;