[mlir][linalg] Fix one more missing NoSideEffect in linalg tensor op

mlir/include/mlir/Dialect/Linalg/IR/LinalgOps.td

[{
       build($_builder, $_state, ValueRange{}, staticShape, elementType);
     }]>
   ];
 
   let hasCanonicalizer = 1;
 }
 
 def Linalg_PadTensorOp : Linalg_Op<"pad_tensor",
-    [AttrSizedOperandSegments]> {
+    [AttrSizedOperandSegments, NoSideEffect]> {
   let summary = "tensor pad operation";
   let description = [{
     `linalg.pad_tensor` is an operation that pads the `source` tensor
     with given `low` and `high` padding config.
 
     The PadTensor operation supports the following arguments:
 
     * source: the "base" tensor on which to pad.

mlir/test/Dialect/Linalg/canonicalize.mlir

#trait = {
   indexing_maps = #accesses,
   iterator_types = ["parallel", "parallel"]
 }
 
 // CHECK-LABEL: func @dead_linalg_tensor
 //   CHECK-NOT:   linalg.fill
 //   CHECK-NOT:   linalg.matmul
 //   CHECK-NOT:   linalg.generic
+//   CHECK-NOT:   linalg.pad_tensor
 //       CHECK:   return
-func @dead_linalg_tensor(%arg0 : tensor<7x7xi32>, %arg1 : tensor<7x7xf32>) {
+func @dead_linalg_tensor(%arg0 : tensor<7x7xi32>, %arg1 : tensor<7x7xf32>,
+                         %arg2: tensor<?x?xf32>, %high : index) {
   %c0_i32 = constant 0 : i32
+  %c0 = constant 0 : index
+  %cst = constant 0.000000e+00 : f32
   %0 = linalg.fill(%arg0, %c0_i32) : tensor<7x7xi32>, i32 -> tensor<7x7xi32>
   %1 = linalg.matmul ins(%arg1, %arg1: tensor<7x7xf32>, tensor<7x7xf32>)
                      outs(%arg1: tensor<7x7xf32>) -> tensor<7x7xf32>
   %2 = linalg.generic #trait outs(%arg0 : tensor<7x7xi32>) {
   ^bb(%3: i32) :
     linalg.yield %3 : i32
   } -> tensor<7x7xi32>
+  %3 = linalg.pad_tensor %arg2 low[%c0, %c0] high[%high, %high] {
+        ^bb0(%arg9: index, %arg10: index):  // no predecessors
+          linalg.yield %cst : f32
+  } : tensor<?x?xf32> to tensor<2x4xf32>
   return
 }