powerpc/fsl/dts: Fix phy-connection-type for fm1mac3
Property phy-connection-type contains invalid value "sgmii-2500" per scheme
defined in file ethernet-controller.yaml.
Correct phy-connection-type value should be "2500base-x".
Signed-off-by: Pali Rohár <pali@kernel.org> Fixes: 04d0e1599142 ("powerpc/mpc85xx: Add MDIO bus muxing support to the board device tree(s)") Acked-by: Scott Wood <oss@buserror.net> Signed-off-by: David S. Miller <davem@davemloft.net>