net: dsa: mt7530: select MEDIATEK_GE_PHY for NET_DSA_MT7530_MDIO

Quoting from commit 4223f8651287 ("net: dsa: mt7530: make NET_DSA_MT7530
select MEDIATEK_GE_PHY"):

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.

Now, the switch can be used without the PHYs but, at the moment, every
hardware design out there that I have seen uses them. For that, it would
make the most sense to force the selection of MEDIATEK_GE_PHY for the MDIO
interface which currently controls the MT7530 and MT7531 switches.

Signed-off-by: Arınç ÜNAL <arinc.unal@arinc9.com>
Reviewed-by: Vladimir Oltean <olteanv@gmail.com>
Link: https://lore.kernel.org/r/20240122053451.8004-1-arinc.unal@arinc9.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>