arm64: Move "nokaslr" over to the early cpufeature infrastructure

arm64: Move "nokaslr" over to the early cpufeature infrastructure

Given that the early cpufeature infrastructure has borrowed quite
a lot of code from the kaslr implementation, let's reimplement
the matching of the "nokaslr" option with it.

Signed-off-by: Marc Zyngier <maz@kernel.org>
Acked-by: Catalin Marinas <catalin.marinas@arm.com>
Acked-by: David Brazdil <dbrazdil@google.com>
Link: https://lore.kernel.org/r/20210208095732.3267263-20-maz@kernel.org
Signed-off-by: Will Deacon <will@kernel.org>