ARM: psci: cpuidle: Enable PSCI CPUidle driver

Allow selection of the PSCI CPUidle in the kernel by updating
the respective Kconfig entry.

Remove PSCI callbacks from ARM/ARM64 generic CPU ops
to prevent the PSCI idle driver from clashing with the generic
ARM CPUidle driver initialization, that relies on CPU ops
to initialize and enter idle states.

Signed-off-by: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
Reviewed-by: Ulf Hansson <ulf.hansson@linaro.org>
Cc: Will Deacon <will@kernel.org>
Cc: Ulf Hansson <ulf.hansson@linaro.org>
Cc: Sudeep Holla <sudeep.holla@arm.com>
Cc: Daniel Lezcano <daniel.lezcano@linaro.org>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: "Rafael J. Wysocki" <rjw@rjwysocki.net>
Signed-off-by: Will Deacon <will@kernel.org>

drivers/cpuidle/Kconfig.arm

@@ -14,7 +14,7 @@ config ARM_CPUIDLE
           provided by architecture code.
 
 config ARM_PSCI_CPUIDLE
-	bool
+	bool "PSCI CPU idle Driver"
 	depends on ARM_PSCI_FW
 	select DT_IDLE_STATES
 	select CPU_IDLE_MULTIPLE_DRIVERS