net: ethernet: ti: am65-cpsw: fixup PHY mode for fixed RGMII TX delay

All am65-cpsw controllers have a fixed TX delay, so the PHY interface
mode must be fixed up to account for this.

Modes that claim to a delay on the PCB can't actually work. Warn people
to update their Device Trees if one of the unsupported modes is specified.

Signed-off-by: Matthias Schiffer <matthias.schiffer@ew.tq-group.com>
Reviewed-by: Maxime Chevallier <maxime.chevallier@bootlin.com>
Reviewed-by: Andrew Lunn <andrew@lunn.ch>
Reviewed-by: Siddharth Vadapalli <s-vadapalli@ti.com>
Link: https://patch.msgid.link/9b3fb1fbf719bef30702192155c6413cd5de5dcf.1750756583.git.matthias.schiffer@ew.tq-group.com


Signed-off-by: Paolo Abeni <pabeni@redhat.com>