Exynos4412 can only use cpuidle when running under a compatible
bootloader/firmware. The Midas family of boards, including Trats2,
have such a firmware, so allow them to use cpuidle.

Leave the Trats2 check there in order to preserve the ABI.
Signed-off-by: NSimon Shields <simon@lineageos.org>
Signed-off-by: NKrzysztof Kozlowski <krzk@kernel.org>