AArch64/ARM64: print BFM instructions as BFI or BFXIL

The canonical form of the BFM instruction is always one of the more explicit
extract or insert operations, which makes reading output much easier.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@207752 91177308-0d34-0410-b5e6-96231b3b80d8
AArch64/ARM64: port basic disassembly tests to ARM64.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@207753 91177308-0d34-0410-b5e6-96231b3b80d8