GlobalISel: mark simple ops legal even on types < 32-bit.

The 32-bit variants of these operations don't depend on the bits not being
operated on, so they also naturally model operations narrower than the actual
register width.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@279760 91177308-0d34-0410-b5e6-96231b3b80d8
7 files changed