net: stmmac: intel: remove unnecessary setting max_speed

net: stmmac: intel: remove unnecessary setting max_speed

Phylink will already limit the MAC speed according to the interface,
so if 2500BASE-X is selected, the maximum speed will be 2.5G.
Similarly, if SGMII is selected, the maximum speed will be 1G.
It is, therefore, not necessary to set a speed limit. Remove setting
plat_dat->max_speed from this glue driver.

Signed-off-by: Russell King (Oracle) <rmk+kernel@armlinux.org.uk>
Reviewed-by: Maxime Chevallier <maxime.chevallier@bootlin.com>
Reviewed-by: Andrew Lunn <andrew@lunn.ch>
Link: https://patch.msgid.link/E1u4dIh-000dT5-Kt@rmk-PC.armlinux.org.uk
Signed-off-by: Jakub Kicinski <kuba@kernel.org>