s390/compat: fix setup_frame32

Git commit c60a03fee0 ("s390: switch to {get,put}_compat_sigset()")
contains a typo and now copies the wrong pointer to user space.
Use the correct pointer instead.

Reported-and-tested-by: Stefan Liebler <stli@linux.vnet.ibm.com>
Fixes: c60a03fee0 ("s390: switch to {get,put}_compat_sigset()")
Cc: <stable@vger.kernel.org> # v4.15+
Cc: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>

arch/s390/kernel/compat_signal.c

@@ -279,7 +279,7 @@ static int setup_frame32(struct ksignal *ksig, sigset_t *set,
 	if (put_compat_sigset((compat_sigset_t __user *)frame->sc.oldmask,
 			      set, sizeof(compat_sigset_t)))
 		return -EFAULT;
-	if (__put_user(ptr_to_compat(&frame->sc), &frame->sc.sregs))
+	if (__put_user(ptr_to_compat(&frame->sregs), &frame->sc.sregs))
 		return -EFAULT;
 
 	/* Store registers needed to create the signal frame */