s390/compat,signal: fix return value of copy_siginfo_(to|from)_user32()

The return value of copy_siginfo_(to|from)_user32() gets passed to
user space, however we do not convert a positive return value from
copy_(to|from)_user to -EFAULT.
Therefore these functions (and the calling system calls) my incorrectly
return a positive number (bytes not copied) instead of -EFAULT.
Signed-off-by: NHeiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: NMartin Schwidefsky <schwidefsky@de.ibm.com>

arch/s390/kernel/compat_signal.c

@@ -99,7 +99,7 @@ int copy_siginfo_to_user32(compat_siginfo_t __user *to, siginfo_t *from)
 			break;
 		}
 	}
-	return err;
+	return err ? -EFAULT : 0;
 }
 
 int copy_siginfo_from_user32(siginfo_t *to, compat_siginfo_t __user *from)
@@ -148,7 +148,7 @@ int copy_siginfo_from_user32(siginfo_t *to, compat_siginfo_t __user *from)
 			break;
 		}
 	}
-	return err;
+	return err ? -EFAULT : 0;
 }
 
 static int save_sigregs32(struct pt_regs *regs, _sigregs32 __user *sregs)