[mlir][Vector] Extend xfer drop unit dim patterns

This patch extends the transfer drop unit dim patterns to support cases where the vector shape should also be reduced
(e.g., transfer_read(memref<1x4x1xf32>, vector<1x4x1xf32>) -> transfer_read(memref<4xf32>, vector<4xf32>).

Reviewed By: hanchung, pzread

Differential Revision: https://reviews.llvm.org/D151007