Revert "ACPI / processor: Make it possible to get APIC ID via GIC"

Revert commit df86f5df (ACPI / processor: Make it possible to get
APIC ID via GIC).

APIC ID refers the hardware ID of the CPU, which means MPIDR on
ARM/ARM64, but in ACPI 5.0, GIC ID feild in GIC structure have
no explicit definition and may not refer to the MPIDR.

Commit df86f5df assumed that gic->gic_id as MPIDR which may not be
the case, so revert it until the explicit definition of GIC structure
is ready.

Signed-off-by: Hanjun Guo <hanjun.guo@linaro.org>
[rjw: Changelog]
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>