cpuidle: cpuidle-arm: remove arm64 support

Since commit 78896146 ("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.ccSigned-off-by: Will Deacon <will@kernel.org>

drivers/cpuidle/Kconfig.arm

@@ -3,7 +3,8 @@
 # ARM CPU Idle drivers
 #
 config ARM_CPUIDLE
-	bool "Generic ARM/ARM64 CPU idle Driver"
+	bool "Generic ARM CPU idle Driver"
+	depends on ARM
 	select DT_IDLE_STATES
 	select CPU_IDLE_MULTIPLE_DRIVERS
 	help