Revert "ARM64: Dynamically allocate cpumasks and increase supported CPUs to 512"

This reverts commit 0499a783.

Enabling CPUMASK_OFFSTACK on arm64 triggers a warning in the
dev_pm_opp_set_config() function followed by a failure to set the
regulators and cpufreq-dt probing error. There is no apparent reason why
this happens, so revert this commit until further investigation.

Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
Reported-by: Marek Szyprowski <m.szyprowski@samsung.com>
Link: https://lore.kernel.org/r/c1f2902d-cefc-4122-9b86-d1d32911f590@samsung.com