[X86][BF16] Fix a typo, NFCI

VR128X is not enabled under AVXNECONVERT.

Author: phoebewang

llvm/lib/Target/X86/X86InstrSSE.td

@@ -8314,7 +8314,7 @@ let Predicates = [HasAVXNECONVERT] in {
        f256mem>, T8;
   defm VCVTNEPS2BF16 : VCVTNEPS2BF16_BASE, VEX, T8, XS, ExplicitVEXPrefix;
 
-  def : Pat<(v8bf16 (X86cvtneps2bf16 (v4f32 VR128X:$src))),
+  def : Pat<(v8bf16 (X86cvtneps2bf16 (v4f32 VR128:$src))),
             (VCVTNEPS2BF16rr VR128:$src)>;
   def : Pat<(v8bf16 (X86cvtneps2bf16 (loadv4f32 addr:$src))),
             (VCVTNEPS2BF16rm addr:$src)>;