powerpc/t1040rdb: added a break in switch case
There should be a break for case PHY_INTERFACE_MODE_SGMII, otherwise it
will fall into case PHY_INTERFACE_MODE_RGMII.
Signed-off-by: Shaohui Xie <Shaohui.Xie@freescale.com>
Reviewed-by: York Sun <yorksun@freescale.com>