powerpc:t4240: MAC9 and MAC10 should not be identified as 1G interface in some case

When using rcw protocols to support 10G on MAC9 and MAC10, these MACs
should not be identified as 1G interface, otherwise, one MAC will be
listed as two Ethernet ports. For example, MAC9 will be listed as
FM1@TGEC1 and FM1@DTSEC9.

Signed-off-by: Ying Zhang <b40530@freescale.com>
Reviewed-by: York Sun <york.sun@nxp.com>