cpuidle: cpuidle-arm: remove arm64 support

cpuidle: cpuidle-arm: remove arm64 support

Since commit 788961462f34 ("ARM: psci: cpuidle: Enable PSCI CPUidle
driver") the generic ARM cpuidle driver doesn't probe anymore because
arm_cpuidle_init() will always return -EOPNOTSUPP. That is, because the
mentioned commit removes the only .cpu_suspend and .cpu_init_idle
provider.

Signed-off-by: Michael Walle <michael@walle.cc>
Reviewed-by: Sudeep Holla <sudeep.holla@arm.com>
Acked-by: Daniel Lezcano <daniel.lezcano@linaro.org>
Link: https://lore.kernel.org/r/20220529181329.2345722-2-michael@walle.cc
Signed-off-by: Will Deacon <will@kernel.org>