ACPI: processor: Move MWAIT quirk out of acpi_processor.c

Commit 2a2a6471

 ("ACPI: Disable MWAIT via DMI on broken Compal board")
introduced a workaround for MWAIT for a specific x86 system.

Move the code outside of acpi_processor.c to acpi/x86/ directory for
consistency and rename the functions associated with it, so their names
start with "acpi_proc_quirk_" to make the goal obvious.

No intentional functional impact.

Suggested-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Signed-off-by: Michal Wilczynski <michal.wilczynski@intel.com>
[ rjw: Subject and changelog edits, two function names changed ]
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>