net: dsa: mt7530: improve comments regarding switch ports

There's no logic to numerically order the CPU ports. Just state the port
number instead.

Remove the irrelevant PHY muxing information from
mt7530_mac_port_get_caps(). Explain the supported MII modes instead.

Remove the out of place PHY muxing information from
mt753x_phylink_mac_config(). The function is for MT7530, MT7531, and the
switch on the MT7988 SoC but there's no PHY muxing on MT7531 or the switch
on the MT7988 SoC.

These comments were gradually introduced with the commits below.
commit ca366d6c ("net: dsa: mt7530: Convert to PHYLINK API")
commit 38f790a8 ("net: dsa: mt7530: Add support for port 5")
commit 88bdef8b ("net: dsa: mt7530: Extend device data ready for adding
a new hardware")
commit c288575f ("net: dsa: mt7530: Add the support of MT7531 switch")

Signed-off-by: Arınç ÜNAL <arinc.unal@arinc9.com>
Acked-by: Daniel Golle <daniel@makrotopia.org>
Reviewed-by: Andrew Lunn <andrew@lunn.ch>
Reviewed-by: Vladimir Oltean <olteanv@gmail.com>
Link: https://lore.kernel.org/r/20240122-for-netnext-mt7530-improvements-1-v3-4-042401f2b279@arinc9.com


Signed-off-by: Jakub Kicinski <kuba@kernel.org>