rewritten the block-grid calculation of xnor kernel
rewritten the block-grid calculation of xnor kernel

hpi-xnor/BMXNet,hpi-xnor/BMXNet,hpi-xnor/BMXNet,hpi-xnor/BMXNet,hpi-xnor/BMXNet,hpi-xnor/BMXNet,hpi-xnor/BMXNet,hpi-xnor/BMXNet,hpi-xnor/BMXNet