net: sparx5: verify RGMII speeds

net: sparx5: verify RGMII speeds

When doing a port config, we verify the port speed against the PHY mode
and supported speeds of that PHY mode. Add checks for the four RGMII phy
modes: RGMII, RGMII_ID, RGMII_TXID and RGMII_RXID.

Reviewed-by: Steen Hegelund <Steen.Hegelund@microchip.com>
Reviewed-by: Horatiu Vultur <horatiu.vultur@microchip.com>
Tested-by: Robert Marko <robert.marko@sartura.hr>
Signed-off-by: Daniel Machon <daniel.machon@microchip.com>
Link: https://patch.msgid.link/20241220-sparx5-lan969x-switch-driver-4-v5-6-fa8ba5dff732@microchip.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>