[AArch64][Builtins] Avoid unnecessary cache cleaning

Use new control bits CTR_EL0.DIC and CTR_EL0.IDC to discover the d-cache
cleaning and i-cache invalidation requirements for instruction-to-data
coherence. This matches the behavior in the latest libgcc.

Author: Shaokun Zhang <zhangshaokun@hisilicon.com>

Reviewed By: peter.smith

Differential Revision: https://reviews.llvm.org/D69247