nfsd4: be forgiving in the absence of the recovery directory
If the recovery directory doesn't exist, then behavior after a reboot
will be suboptimal. But it's unnecessarily harsh to then prevent the
nfsv4 server from working at all. Instead just print a warning
(already done in nfsd4_init_recdir()) and soldier on.
Tested-by: Lior <lior@tonian.com>
Signed-off-by: J. Bruce Fields <bfields@redhat.com>