powerpc/mpc85xx: Add RCW bits and registers for SerDes for corenet2

Corenet 2nd generation Chassis has different RCW and registers for SerDes.

Signed-off-by: York Sun <yorksun@freescale.com>
Signed-off-by: Prabhakar Kushwaha <prabhakar@freescale.com>
Signed-off-by: Andy Fleming <afleming@freescale.com>