just 0 should be used to represent cleared bits

* ETHER_CLK_SEL_DIV_SEL_20
* ETHER_CLK_SEL_TX_CLK_EXT_SEL_IN
* ETHER_CLK_SEL_RX_CLK_EXT_SEL_IN
* ETHER_CLK_SEL_TX_CLK_O_TX_I
* ETHER_CLK_SEL_RMII_CLK_SEL_IN

Fixes: b38dd98f ("net: stmmac: Add Toshiba Visconti SoCs glue driver")
Signed-off-by: Yuji Ishikawa <yuji2.ishikawa@toshiba.co.jp>
Reviewed-by: Nobuhiro Iwamatsu <nobuhiro1.iwamatsu@toshiba.co.jp>
Signed-off-by: David S. Miller <davem@davemloft.net>