drivers: intc_gicv3: fix gic_rdists[cpu] points to a wrong address

In old way, gic_rdists[cpu] is calculated via MPIDR_TO_CORE(), but in
real hardware, MPIDR_TO_CORE() isn't a value increment from 0 one by
one, and that will lead gic_rdists[cpu] to point to a wrong address.

GICv3 provides the register GICR_TYPER[1] and it has a field named
Affinity_Value. This field can help to determine where gic_rdists[cpu]
should point.

Signed-off-by: Huifeng Zhang <Huifeng.Zhang@arm.com>