powerpc/mpc85xx: Few updates for B4860 cpu changes

powerpc/mpc85xx: Few updates for B4860 cpu changes

- Added some more serdes1 and serdes2 combinations
  serdes1= 0x2c, 0x2d, 0x2e
  serdes2= 0x7a, 0x8d, 0x98
- Updated Number of DDR controllers to 2.
- Added FMAN file for B4860, drivers/net/fm/b4860.c

Signed-off-by: York Sun <[email protected]>
Signed-off-by: Shaveta Leekha <[email protected]>
Signed-off-by: Prabhakar Kushwaha <[email protected]>
Signed-off-by: Sandeep Singh <[email protected]>
Signed-off-by: Poonam Aggrwal <[email protected]>
Signed-off-by: Andy Fleming <[email protected]>