ACPI: x86: cmos_rtc: Create a CMOS RTC platform device

ACPI: x86: cmos_rtc: Create a CMOS RTC platform device

Make the CMOS RTC ACPI scan handler create a platform device that will
be used subsequently by rtc-cmos for driver binding on x86 systems with
ACPI and update add_rtc_cmos() to skip registering a fallback platform
device for the CMOS RTC when the above one has been registered.

Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Acked-by: Dave Hansen <dave.hansen@linux.intel.com> # x86
Link: https://patch.msgid.link/1962427.tdWV9SEqCh@rafael.j.wysocki