Freescale t104x: Do not exclude SGMII

fman_port_enet_if() tests if FM1_DTSEC2 or FM1_DTSEC4 uses
RGMII or MII and if not returns PHY_INTERFACE_MODE_NONE.
This excludes testing for SGMII further down.

Remove the unconditional "else return PHY_INTERFACE_MODE_NONE"
so SGMII can be tested too.

Signed-off-by: Joakim Tjernlund <Joakim.Tjernlund@transmode.se>
Reviewed-by: York Sun <yorksun@freescale.com>