net: dsa: mt753x: remove mt753x_phylink_pcs_link_up()

Remove the mt753x_phylink_pcs_link_up() function for two reasons:

1) priv->pcs[i].pcs.neg_mode is set true, meaning it doesn't take a
   MLO_AN_FIXED anymore, but one of PHYLINK_PCS_NEG_*. However, this
   is inconsequential due to...
2) priv->pcs[port].pcs.ops is always initialised to point at
   mt7530_pcs_ops, which does not have a pcs_link_up() member.

So, let's remove mt753x_phylink_pcs_link_up() entirely.

Signed-off-by: Russell King (Oracle) <rmk+kernel@armlinux.org.uk>
Reviewed-by: Vladimir Oltean <vladimir.oltean@nxp.com>
Reviewed-by: Florian Fainelli <florian.fainelli@broadcom.com>
Link: https://lore.kernel.org/r/E1qlTQS-008BWe-Va@rmk-PC.armlinux.org.uk


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