[mlir] Make sure linearizeCollapsedDims doesn't drop input map dims

The new affine map generated by linearizeCollapsedDims should not drop
dimensions. We need to make sure we create a map with at least as many
dimensions as the source map. This prevents
FoldProducerReshapeOpByLinearization from generating invalid IR.

This solves regression in IREE due to https://github.com/llvm/llvm-project/commit/e4e4da86aff5606ef792d987a3ec85639219228c

Reviewed By: mravishankar

Differential Revision: https://reviews.llvm.org/D114838