llvm: Revert "[HardwareLoops] Change order of SCEV expression construction for InitLoopCount."

Reverts llvm commit 42eaf4fe0adef3344adfd9fbccd49f325cb549ef, pointed
from bisect as source of regression that causes liblzma to compress/
uncompress incorrectly. It's know to affect powerpc64 BE only.

The patch unbreaks FreeBSD powerpc64 installation media, since
bsdinstall can't uncompress the *.txz produced by FreeBSD CI. It's
probably miscompiling other software bas well.

Upstream PR: https://bugs.llvm.org/show_bug.cgi?id=51714

Reviewed by: dim
MFC after: 2 days
Sponsored by: Instituto de Pesquisas Eldorado (eldorado.org.br)
Differential Revision: https://reviews.freebsd.org/D31804