[mlir][linalg] Canonicalize dim ops of tiled_loop block args

E.g.:
```
%y = ... : tensor<...>
linalg.tiled_loop ... ins(%x = %y : tensor<...>) {
  tensor.dim %x, %c0 : tensor<...>
}
```

is rewritten to:
```
%y = ... : tensor<...>
linalg.tiled_loop ... ins(%x = %y : tensor<...>) {
  tensor.dim %y, %c0 : tensor<...>
}
```

Differential Revision: https://reviews.llvm.org/D108272