[NFC] Follow up on D87111 - Add an option for unrolling loops up to a factor - CR issues addressed.

Addressed some CR issues pointed out in D87111. Formatting and other nits.
The original Diff D87111 - Add an option for unrolling loops up to a factor.

Reviewed By: bondhugula

Differential Revision: https://reviews.llvm.org/D87313