[AArch64InstPrinter] prefer bfi to bfc for < armv8.2-a

Summary:
Fixes pr/42576.

Link: https://github.com/ClangBuiltLinux/linux/issues/697

Reviewers: t.p.northover

Reviewed By: t.p.northover

Subscribers: kristof.beyls, hiraditya, llvm-commits, srhines

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D68356

llvm-svn: 373655