nfsd: drop inode parameter from nfsd4_change_attribute()

The inode that nfs4_open_delegation() passes to this function is
wrong, which throws off the result. The inode will end up getting a
directory-style change attr instead of a regular-file-style one.

Fix up nfs4_delegation_stat() to fetch STATX_MODE, and then drop the
inode parameter from nfsd4_change_attribute(), since it's no longer
needed.

Fixes: c5967721 ("NFSD: handle GETATTR conflict with write delegation")
Signed-off-by: Jeff Layton <jlayton@kernel.org>
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>