Make MediaTek MT753x DSA driver enable MediaTek Gigabit PHYs driver to
properly control MT7530 and MT7531 switch PHYs.

A noticeable change is that the behaviour of switchport interfaces going
up-down-up-down is no longer there.

Fixes: b8f126a8 ("net-next: dsa: add dsa support for Mediatek MT7530 switch")
Signed-off-by: Arınç ÜNAL <arinc.unal@arinc9.com>
Reviewed-by: Andrew Lunn <andrew@lunn.ch>
Reviewed-by: Florian Fainelli <f.fainelli@gmail.com>
Link: https://lore.kernel.org/r/20220129062703.595-1-arinc.unal@arinc9.comSigned-off-by: Jakub Kicinski <kuba@kernel.org>