[X86][FMA][FMA4]: Adding full coverage of MC encoding for the FMA, FM…

…A4 isa sets.<NFC>

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

Change-Id: Ie39c0edce69ad647076b3d4e816948b2b6e1a9e4
llvm-svn: 320016