[X86] Correct the load folding flags for xmm fp->mmx conversion instructions.

[X86] Correct the load folding flags for xmm fp->mmx conversion instructions.

The instructions that load 64-bits or an xmm register should be TB_NO_REVERSE to avoid the load being widened during unfold. The instructions that load 128-bits need to ensure 128-bit alignment.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@321956 91177308-0d34-0410-b5e6-96231b3b80d8