nfsd: fix lost nfserrno() call in nfsd_setattr()

There is a regression in
	208d0acc 2014-01-07 nfsd4: break only delegations when appropriate
which deletes an nfserrno() call in nfsd_setattr() (by accident,
probably), and NFSD becomes ignoring an error from VFS.

Signed-off-by: J. Bruce Fields <bfields@redhat.com>