net: stmmac: visconti: make phy_intf_sel local

net: stmmac: visconti: make phy_intf_sel local

There is little need to have phy_intf_sel as a member of struct
visconti_eth when we have the PHY interface mode available from
phylink in visconti_eth_set_clk_tx_rate(). Without multiple
interface support, phylink is fixed to supporting only
plat->phy_interface, so we can be sure that "interface" passed
into this function is the same as plat->phy_interface.

Make phy_intf_sel local to visconti_eth_init_hw() and clean up.

Signed-off-by: Russell King (Oracle) <rmk+kernel@armlinux.org.uk>
Reviewed-by: Andrew Lunn <andrew@lunn.ch>
Link: https://patch.msgid.link/E1uRH2G-004UyY-GD@rmk-PC.armlinux.org.uk
Signed-off-by: Jakub Kicinski <kuba@kernel.org>