ACPI: Add CMOS RTC Operation Region handler support

On HP Folio 13-2000, the BIOS defines a CMOS RTC Operation Region and
the EC's _REG methord accesses that region.  Thus an appropriate
address space handler must be registered for that region before the
EC driver is loaded.

Introduce a mechanism for adding CMOS RTC address space handlers.
Register an ACPI scan handler for CMOS RTC devices such that, when
a device of that kind is detected during an ACPI namespace scan, a
common CMOS RTC operation region address space handler will be
installed for it.

References: https://bugzilla.kernel.org/show_bug.cgi?id=54621
Reported-and-tested-by: Stefan Nagy <public@stefan-nagy.at>
Signed-off-by: Lan Tianyu <tianyu.lan@intel.com>
Cc: 3.9+ <stable@vger.kernel.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>