CVE-2024-46690

In the Linux kernel, the following vulnerability has been resolved:

nfsd: fix nfsd4_deleg_getattr_conflict in presence of third party lease

It is not safe to dereference fl->c.flc_owner without first confirming
fl->fl_lmops is the expected manager.  nfsd4_deleg_getattr_conflict()
tests fl_lmops but largely ignores the result and assumes that flc_owner
is an nfs4_delegation anyway.  This is wrong.

With this patch we restore the "!= &nfsd_lease_mng_ops" case to behave
as it did before the change mentioned below.  This is the same as the
current code, but without any reference to a possible delegation.