Fix type typo in rmsnorm (PaddlePaddle#1119)

Initially the variable `h4` is `half4`, but its last two fields are not used. Based on the semantics and the context, I believe it should be `half2`.

Author: abcdabcd987

tools/util/include/cutlass/util/device_rmsnorm.h

@@ -98,7 +98,7 @@ __global__ void rmsnorm_twoPassAlgo_e8(float4 *output, const float4 *input,
     half2 *h1 = (half2 *)&tmp.x;
     half2 *h2 = (half2 *)&tmp.y;
     half2 *h3 = (half2 *)&tmp.z;
-    half4 *h4 = (half4 *)&tmp.w;
+    half2 *h4 = (half2 *)&tmp.w;
 
     h1->x = half(static_cast<float>(l1->x) * s_mean * static_cast<float>(g1->x));
     h1->y = half(static_cast<float>(l1->y) * s_mean * static_cast<float>(g1->y));