[MLIR][Vector] Fix crash in operatesOnSuperVectorsOf on rank-mismatched shaped (#183967)
The `operatesOnSuperVectorsOf` function in VectorUtils.cpp contained an
assertion that fired when a `vector.transfer` operation's vector type
had a different rank (or non-divisible shape) from the sub-vector type
supplied by the caller:
assert((ratio || \!mustDivide) &&
"vector.transfer operation in which super-vector size is not an"
" integer multiple of sub-vector size");
This assertion was incorrect because the function's callers (e.g., the
affine super-vectorizer) legitimately pass transfer ops whose vector
type doesn't match the requested sub-vector shape. In those cases the
correct answer is simply that the op does not operate on a super-vector
of that sub-vector type, so `operatesOnSuperVectorsOf` should return
`false`.
Remove the assert return `false` when `computeShapeRatio` produces no
result, and remove the now-unused `mustDivide` variable.
Fixes #149327
Fixes #131096