[S390] avoid default_llseek in s390 drivers

Use nonseekable_open for a couple of s390 device drivers. This avoids
the use of default_llseek function which has a dependency on the BKL.

Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>

arch/s390/hypfs/inode.c

@@ -145,7 +145,7 @@ static int hypfs_open(struct inode *inode, struct file *filp)
 		}
 		mutex_unlock(&fs_info->lock);
 	}
-	return 0;
+	return nonseekable_open(inode, filp);
 }
 
 static ssize_t hypfs_aio_read(struct kiocb *iocb, const struct iovec *iov,