ACPI: processor: fix acpi_get_cpuid for UP processor

ACPI: processor: fix acpi_get_cpuid for UP processor

For UP processor, it is likely that no _MAT method or MADT table defined.
So currently acpi_get_cpuid(...) always return -1 for UP processor.
This is wrong. It should return valid value for CPU0.

In the other hand, BIOS may define multiple CPU handles even for UP
processor, for example

        Scope (_PR)
        {
            Processor (CPU0, 0x00, 0x00000410, 0x06) {}
            Processor (CPU1, 0x01, 0x00000410, 0x06) {}
            Processor (CPU2, 0x02, 0x00000410, 0x06) {}
            Processor (CPU3, 0x03, 0x00000410, 0x06) {}
        }

We should only return valid value for CPU0's acpi handle.
And return invalid value for others.

http://marc.info/?t=132329819900003&r=1&w=2

Cc: stable@vger.kernel.org
Reported-and-tested-by: wallak@free.fr
Signed-off-by: Lin Ming <ming.m.lin@intel.com>
Signed-off-by: Len Brown <len.brown@intel.com>