dt-bindings: net: faraday,ftgmac100: Add phys mode

Aspeed device supports rgmii, rgmii-id, rgmii-rxid, rgmii-txid so
document them.

Acked-by: Rob Herring (Arm) <robh@kernel.org>
Signed-off-by: Ninad Palsule <ninad@linux.ibm.com>
Reviewed-by: Andrew Lunn <andrew@lunn.ch>
Link: https://patch.msgid.link/20250203151306.276358-2-ninad@linux.ibm.com


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