Same SoC has different personality by creating different number of:
- cores
- clusters.

As a result, the platform specific power domain tree will be created
after identify the personality of the SoC.
Hence, platform specific power domain tree may not be same for all the
personality of the soc.

Thus, psci library code will deduce the 'plat_core_count', while
populating the power domain tree topology and return the number of
cores.

PLATFORM_CORE_COUNT will still be valid for a SoC, such that
psci_plat_core_count <= PLATFORM_CORE_COUNT.

PLATFORM_CORE_COUNT will continued to be defined by platform to create
the data structures.
Signed-off-by: Pankaj Gupta <pankaj.gupta@nxp.com>
Change-Id: I1f5c47647631cae2dcdad540d64cf09757db7185