powerpc/mpc85xx:Avoid fix clk groups for Cluster & HW accelerator

powerpc/mpc85xx:Avoid fix clk groups for Cluster & HW accelerator

CHASSIS2 architecture never fix clock groups for Cluster and hardware
  accelerator like PME, FMA. These are SoC defined. SoC defines :-
    - NUM of PLLs present in the system
    - Clusters and their Clock group
    - hardware accelerator and their clock group
      if no clock group, then platform clock divider for FMAN, PME

Signed-off-by: Prabhakar Kushwaha <prabhakar@freescale.com>