ACPI: Fix section mismatch error for acpi_early_processor_set_pdc()

Alex Chiang introduced acpi_early_processor_set_pdc() in commit:
 ACPI: processor: call _PDC early
 78f16996

But this results in a section mismatch:

WARNING: drivers/acpi/acpi.o(.text+0xa9c1): Section mismatch in reference from the
function acpi_early_processor_set_pdc() to the variable .cpuinit.data:processor_idle_dmi_table
The function acpi_early_processor_set_pdc() references
the variable __cpuinitdata processor_idle_dmi_table.
This is often because acpi_early_processor_set_pdc lacks a __cpuinitdata
annotation or the annotation of processor_idle_dmi_table is wrong.

The only caller of acpi_early_processor_set_pdc() is acpi_bus_init() which
is an "__init" function. So the correct fix here is to mark
acpi_early_processor_set_pdc() "__init" too.

Signed-off-by: Tony Luck <tony.luck@intel.com>
Acked-by: Alex Chiang <achiang@hp.com>
Signed-off-by: Len Brown <len.brown@intel.com>