[X86][FMA][FMA4]: Adding full coverage of MC encoding for the FMA, FMA4 isa sets.<NFC>
Adding MC regressions tests to cover the FMA and FMA4 ISA sets.
This patch is part of a larger task to cover MC encoding of all X86 ISA Sets starting revision https://reviews.llvm.org/D39952
Reviewers: craig.topper, RKSimon, zvi
Differential Revision: https://reviews.llvm.org/D40880