rt: fixup build issues with 5.2-stable

This -rt commit:

commit 037e1e52
Author: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Date:   Fri Oct 20 11:29:53 2017 +0200

    fs/dcache: disable preemption on i_dir_seq's write side

bumps into this stable backport:

commit 60624198


Author: Al Viro <viro@zeniv.linux.org.uk>
Date:   Sun Sep 15 12:12:39 2019 -0400

    Fix the locking in dcache_readdir() and friends

Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com>
Signed-off-by: Bruce Ashfield <bruce.ashfield@gmail.com>