net: dsa: b53: prevent GMII_PORT_OVERRIDE_CTRL access on BCM5325

net: dsa: b53: prevent GMII_PORT_OVERRIDE_CTRL access on BCM5325

[ Upstream commit 37883bbc45a8555d6eca88d3a9730504d2dac86c ]

BCM5325 doesn't implement GMII_PORT_OVERRIDE_CTRL register so we should
avoid reading or writing it.
PORT_OVERRIDE_RX_FLOW and PORT_OVERRIDE_TX_FLOW aren't defined on BCM5325
and we should use PORT_OVERRIDE_LP_FLOW_25 instead.

Reviewed-by: Florian Fainelli <florian.fainelli@broadcom.com>
Signed-off-by: Álvaro Fernández Rojas <noltari@gmail.com>
Link: https://patch.msgid.link/20250614080000.1884236-12-noltari@gmail.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>