[mlir][Vector] Remove 'lower-permutation-maps' option from VectorToSCF

This patch is part of a larger simplification effort of vector transfer
operations. It removes the flag `lower-permutation-maps` from
VectorToSCF conversion and enables the lowering of permutation maps
by default. This means that VectorToSCF will always lower permutation
maps to independent broadcast/transpose operations before lowering
vector operations to SCF.

Reviewed By: nicolasvasilache

Differential Revision: https://reviews.llvm.org/D138742