[X86] AVX512: Move compressed displacement logic to TD

[X86] AVX512: Move compressed displacement logic to TD

This does not actually move the logic yet but reimplements it in the Tablegen
language.  Then asserts that the new implementation results in the same value.

The next patch will remove the assert and the temporary use of the TSFlags and
remove the C++ implementation.

The formula requires a limited form of the logical left and right operators.
I implemented these with the bit-extract/insert operator (i.e. blah{bits}).

No functional change.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@213278 91177308-0d34-0410-b5e6-96231b3b80d8