powerpc/mpc85xx:Avoid hardcoded init for serdes block 1 & 2

It is not necessary for all processor to have serdes block 1 & 2.
They may have only one serdes block.

So, put serdes block 1 & 2 related code under defines

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