metal : fix group_norm support condition (llama/0)

ggml/src/ggml-metal/ggml-metal.m

@@ -1004,9 +1004,10 @@ static bool ggml_metal_supports_op(const struct ggml_backend_metal_device_contex
             return ggml_is_contiguous(op->src[0]);
         case GGML_OP_SUM_ROWS:
         case GGML_OP_SOFT_MAX:
-        case GGML_OP_RMS_NORM:
         case GGML_OP_GROUP_NORM:
             return has_simdgroup_reduction;
+        case GGML_OP_RMS_NORM:
+            return has_simdgroup_reduction && (op->ne[0] % 4 == 0);
         case GGML_OP_ARGMAX:
         case GGML_OP_NORM:
         case GGML_OP_ROPE: