[AArch64] Replace AEK_CRYPTO with relevant features in cpu definitions

This replaces AEK_CRYPTO in the AArch64TargetParser definitions,
replacing the composite Crypto features with the constituent parts.
AEK_CRYPTO is replaced with either AEK_AES | AEK_SHA2 or AEK_AES |
AEK_SHA2 | AEK_SHA3 | AEK_SHA4 depending on if the cpu is Arm-v8.4+.
This helps get the features correct in some more places like
target(cpu=..) attributes.

Otherwise this is hopefully an NFC for -mcpu options but seems like a
cleaner design.

Differential Revision: https://reviews.llvm.org/D142548