arm64: cpufeature: Factor out checking of AArch32 features

update_cpu_features() is pretty large, so split out the checking of the
AArch32 features into a separate function and call it after checking the
AArch64 features.

Tested-by: Sai Prakash Ranjan <saiprakash.ranjan@codeaurora.org>
Reviewed-by: Suzuki K Poulose <suzuki.poulose@arm.com>
Link: https://lore.kernel.org/r/20200421142922.18950-6-will@kernel.org


Signed-off-by: Will Deacon <will@kernel.org>