powerpc/mpc85xx:Fix Core cluster configuration loop

powerpc/mpc85xx:Fix Core cluster configuration loop

Different personalities/derivatives of SoC may have reduced cluster. But it is
not necessary for last valid DCFG_CCSR_TP_CLUSTER register to have
DCFG_CCSR_TP_CLUSTER[EOC] bit set to represent "End of Clusters".

EOC bit can still be set in last DCFG_CCSR_TP_CLUSTER register of orignal SoC
which may not be valid for the personality.
So add initiator type check to find valid cluster.

Signed-off-by: Prabhakar Kushwaha <prabhakar@freescale.com>
Signed-off-by: Poonam Aggrwal <poonam.aggrwal@freescale.com>
Signed-off-by: Andy Fleming <afleming@freescale.com>