ACPI: EC: Register a platform device for ECDT EC

ACPI: EC: Register a platform device for ECDT EC

To facilitate converting the ACPI EC driver into a platform one,
modify acpi_bus_register_early_device(), used by acpi_ec_ecdt_start()
for creating a struct acpi_device to represent the "early" EC based
on the ECDT ACPI table, to carry out the default ACPI enumeration for
the given device which will cause a platform device to be registered
for it.

No intentional functional impact.

Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Link: https://patch.msgid.link/2397353.ElGaqSPkdT@rafael.j.wysocki