[X86] Remove two feature flags that covered sets of instructions that have no pattern...

[X86] Remove two feature flags that covered sets of instructions that have no patterns or intrinsics. Since we don't check feature flags in the assembler parser for any instruction sets, these flags don't provide any value. This frees up 2 of the fully utilized feature flags.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@228282 91177308-0d34-0410-b5e6-96231b3b80d8