[mlir][Vector] Generalize AVX2 transpose lowering to n-D vectors

[mlir][Vector] Generalize AVX2 transpose lowering to n-D vectors

The existing AVX2 lowering patterns for the transpose op only triggers if the
input vector is 2-D. This patch extends the patterns to trigger for n-D vectors
which are effectively 2-D vectors (e.g., vector<1x4x1x8x1). The main constraint
for the generalized AVX2 patterns to be applicable to these vectors is that the
dimensions that are greater than one must be transposed. Otherwise, the existing
patterns are not applicable.

Reviewed By: nicolasvasilache

Differential Revision: https://reviews.llvm.org/D119505