Change mixed_D default value to false

Author: avbokovoy

fbgemm_gpu/codegen/training/backward/embedding_backward_dense_host_cpu.cpp

@@ -172,7 +172,7 @@ Tensor split_embedding_codegen_lookup_dense_function(
     c10::SymInt /* max_B = -1 */,
     c10::SymInt /* max_B_feature_rank = -1 */,
     c10::SymInt /* vbe_output_size = -1 */,
-    bool /* mixed_D = true */) {
+    bool /* mixed_D = false */) {
   return SplitLookupFunction_Dense_Op::apply(
       host_weights,
       weights_offsets,

fbgemm_gpu/codegen/training/backward/embedding_backward_split_host_template.cpp

@@ -1116,7 +1116,7 @@ Tensor {{ bwd_mdesc }}_embedding_codegen_lookup_{{ optimizer }}_function(
     {%- else %}
     const c10::SymInt vbe_output_size = -1,
     {%- endif %}
-    const bool mixed_D = true
+    const bool mixed_D = false
 ) {
   // TODO: refactor into macro
   {%- if has_gpu_support %}