[PowerPC] Do not emit record-form rotates when record-form andi suffices

Up until Power9, the performance profile for rlwinm., rldicl. and andi. looked
more or less equivalent. However with Power9, the rotates are still 2-way
cracked whereas the and-immediate is not.

This patch just ensures that we don't emit record-form rotates when an andi.
is adequate.

As first pointed out by Carrot in https://bugs.llvm.org/show_bug.cgi?id=30833
(this patch is a fix for that PR).

Differential Revision: https://reviews.llvm.org/D43977


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@326736 91177308-0d34-0410-b5e6-96231b3b80d8