kernel: arm64: acpi: Harden get_cpu_for_acpi_id() against missing CPU entry

In the Linux kernel, the following vulnerability has been resolved: arm64: acpi: Harden getcpuforacpiid against missing CPU entry In a review discussion of the changes to support vCPU hotplug where a check was added on the GICC being enabled if was online, it was noted that there is need to map...