Revert "ACPI: EC: Do not clear boot_ec_is_ecdt in acpi_ec_add()"

This reverts commit e8eab1ac which is
commit 65a691f5 upstream.

Rafael writes:
	It has not been marked for -stable or otherwise requested to be
	included AFAICS.  Also it depends on other mainline commits that
	have not been included into 5.6.5.

Reported-by: Toralf Förster <toralf.foerster@gmx.de>
Reported-by: Rafael J. Wysocki <rafael@kernel.org>
Cc: Sasha Levin <sashal@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>