[AArch64] Enable LSLFast for modern OoO cpus

This patch enables the LSLFast feature for Cortex-A76, Cortex-A77,
Cortex-A78, Cortex-A78C, Cortex-A710, Cortex-X1, Cortex-X2, Neoverse N1,
Neoverse N2, Neoverse V1 and the Neoverse 512TB pseudo-cpu, in-line with
the software optimization guides for those CPUs.

Differntial revision: https://reviews.llvm.org/D134273