ARM: cpuidle: Enable the ARM64 driver for both ARM32/ARM64

ARM32 and ARM64 have the same DT definitions and the same approaches.

The generic ARM cpuidle driver can be put in common for those two
architectures.

Signed-off-by: Daniel Lezcano <daniel.lezcano@linaro.org>
Acked-by: Kevin Hilman <khilman@linaro.org>
Acked-by: Rob Herring <robherring2@gmail.com>
Acked-by: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
Tested-by: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
diff --git a/arch/arm64/configs/defconfig b/arch/arm64/configs/defconfig
index be1f12a..af6a452 100644
--- a/arch/arm64/configs/defconfig
+++ b/arch/arm64/configs/defconfig
@@ -48,7 +48,7 @@
 # CONFIG_CORE_DUMP_DEFAULT_ELF_HEADERS is not set
 CONFIG_COMPAT=y
 CONFIG_CPU_IDLE=y
-CONFIG_ARM64_CPUIDLE=y
+CONFIG_ARM_CPUIDLE=y
 CONFIG_NET=y
 CONFIG_PACKET=y
 CONFIG_UNIX=y