net: phy: Mask-out non-compatible modes when setting the max-speed

When setting a PHY's max speed using either the max-speed DT property
or ethtool, we should mask-out all non-compatible modes according to the
settings table, instead of just the 10/100BASET modes.

Signed-off-by: Maxime Chevallier <maxime.chevallier@bootlin.com>
Suggested-by: Russell King <rmk+kernel@armlinux.org.uk>
Reviewed-by: Andrew Lunn <andrew@lunn.ch>
Signed-off-by: David S. Miller <davem@davemloft.net>