Disable region simplification in --aie-substitute-shim-dma-allocations pass

[andrej]

The pattern rewriter in this pass previously also performed region simplification, which caused an assertion error if the MLIR contained blocks with input arguments, such as generated by:

          %7 = scf.if %6 -> (memref<64x32xf32>) {
            scf.yield %C_L1L2_0_0_buff_0 : memref<64x32xf32>
          } else {
            scf.yield %C_L1L2_0_0_buff_1 : memref<64x32xf32>
          }

This fixes that issue. I don't fully understand why the issue exists with region simplification, but the point of this pass is not to simplify regions anyways, so it is fine to disable.

[fifield]

Seems like red-flag that the IR is left in a bad state somewhere. Do you have a failing (fixed) test you can add to the PR?