net: stmmac: dma channel control register need to be init first

stmmac_init_chan() needs to be called before stmmac_init_rx_chan() and
stmmac_init_tx_chan(). This is because if PBLx8 is to be used,
"DMA_CH(#i)_Control.PBLx8" needs to be set before programming
"DMA_CH(#i)_TX_Control.TxPBL" and "DMA_CH(#i)_RX_Control.RxPBL".

Fixes: 47f2a9ce ("net: stmmac: dma channel init prepared for multiple queues")
Reviewed-by: Zhang, Baoli <baoli.zhang@intel.com>
Signed-off-by: Ong Boon Leong <boon.leong.ong@intel.com>
Signed-off-by: Weifeng Voon <weifeng.voon@intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>