arm64: defconfig: Drop ARM_CPUIDLE(generic idle driver) config

arm64: defconfig: Drop ARM_CPUIDLE(generic idle driver) config

Since commit 788961462f34 ("ARM: psci: cpuidle: Enable PSCI CPUidle
driver") the generic ARM cpuidle driver probe no longer worked on
ARM64. It was however left enabled with the driver failing to probe
successfully. However the commit 51280acad855 ("cpuidle: cpuidle-arm:
remove arm64 support") removed the Kconfig option so that it is no
longer enabled for arm64 platforms.

Drop the disabled/unavailable ARM_CPUIDLE from the defconfig.

Signed-off-by: Sudeep Holla <sudeep.holla@arm.com>
Link: https://lore.kernel.org/r/20220822121604.2213778-1-sudeep.holla@arm.com'
Signed-off-by: Arnd Bergmann <arnd@arndb.de>