nfsd: Drop the client reference in client_states_open()

nfsd: Drop the client reference in client_states_open()

commit 1f941b2c23fd34c6f3b76d36f9d0a2528fa92b8f upstream.

In error path, call drop_client() to drop the reference
obtained by get_nfsdfs_clp().

Fixes: 78599c42ae3c ("nfsd4: add file to display list of client's opens")
Cc: stable@vger.kernel.org
Reviewed-by: Jeff Layton <jlayton@kernel.org>
Signed-off-by: Haoxiang Li <lihaoxiang@isrc.iscas.ac.cn>
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>