[LV] Remove what seems like stale code in collectElementTypesForWidening.

This was originally added in rG22174f5d5af1eb15b376c6d49e7925cbb7cca6be
although that patch doesn't really mention any reasons for ignoring the
pointer type in this calculation if the memory access isn't consecutive.

Reviewed By: david-arm

Differential Revision: https://reviews.llvm.org/D115356