[mlir][Vector] Avoid infinite loop in InnerOuterDimReductionConversion.

This patterns tries to convert an inner (outer) dim reduction to an
outer (inner) dim reduction. Doing this on a 1D or 0D vector results
in an infinite loop since the converted op is same as the original
operation. Just returning failure when source rank <= 1 fixes the
issue.

Differential Revision: https://reviews.llvm.org/D115426