[AArch64] Remove unused feature flags from AArch64TargetInfo

This removes two feature flags from `AArch64TargetInfo` class:

- `HasHBC`: this feature does not involve generating any IR intrinsics,
so clang does not need to know about whether it is set

- `HasCrypto`: this feature is deprecated in favor of finer grained
features such as AES, SHA2, SHA3 and SM4. The associated ACLE macro
__ARM_FEATURE_CRYPTO is thus no longer used.

Differential Revision: https://reviews.llvm.org/D118757