[LoopRotate] Fix incorrect SCEV invalidation in loop rotation

LoopRotate only invalidates innermost loops while the changes that it makes may
also affert any of this parents. With patch rL329047, SCEV becomes much smarter
about calculation of exit counts for outer loops, so we cannot assume that they are
not affected.

Differential Revision: https://reviews.llvm.org/D45945

llvm-svn: 330582