NFSv4: Propagate the error NFS4ERR_BADOWNER to nfs4_do_setattr

This will be required in order to switch uid/gid mapping back on if the
admin has tried to disable it.

Note that we also propagate NFS4ERR_BADNAME at the same time, in order to
work around a Linux server bug.

Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>