arm64: cpufeature: Use defined macro instead of magic numbers

Use defined macro to simplify the code and make it more readable.

Cc: Marc Zyngier <maz@kernel.org>
Signed-off-by: Shaokun Zhang <zhangshaokun@hisilicon.com>
Link: https://lore.kernel.org/r/1626415089-57584-1-git-send-email-zhangshaokun@hisilicon.com


Acked-by: Will Deacon <will@kernel.org>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>