net: phylink: remove pcs_ops member

Remove the pcs_ops member from struct phylink, using the one stored in
struct phylink_pcs instead.

Reviewed-by: Andrew Lunn <andrew@lunn.ch>
Signed-off-by: Russell King (Oracle) <rmk+kernel@armlinux.org.uk>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>