[AMD][Fix] Restore aiter-padded MoE weight dims for serialized checkpoints (#33090)

AMD only change

python/sglang/srt/layers/quantization/quark/schemes/quark_w4a4_mxfp4_moe.py

@@ -196,9 +196,18 @@ class QuarkW4A4MXFp4MoE(QuarkMoEScheme):
         extra_weight_attrs["weight_loader"] = weight_loader
 
         # WEIGHTS
+        # Serialized MXFP4 must keep the aiter-aligned dims from
+        # get_moe_weight_sizes(): w13_weight_scale / w2_weight_scale below are
+        # still sized off w13_up_dim / w2_down_dim, and `weight_padded` is
+        # advertised to the loader, so allocating the raw (unpadded) dims here
+        # desyncs the weights from their scales.
         w13_shape = (
             num_experts,
-            2 * intermediate_size_per_partition,
+            (
+                w13_up_dim
+                if self.is_checkpoint_mxfp4_serialized
+                else 2 * intermediate_size_per_partition
+            ),
             hidden_size // 2 if self.is_checkpoint_mxfp4_serialized else hidden_size,
         )
         w13_weight = torch.nn.Parameter(
@@ -217,7 +226,7 @@ class QuarkW4A4MXFp4MoE(QuarkMoEScheme):
             num_experts,
             hidden_size,
             (
-                intermediate_size_per_partition // 2
+                w2_down_dim
                 if self.is_checkpoint_mxfp4_serialized
                 else intermediate_size_per_partition
             ),