[ARM] GlobalISel: Mark shifts as legal for s32

The new legalize combiner introduces shifts all over the place, so we
should support them sooner rather than later.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@315064 91177308-0d34-0410-b5e6-96231b3b80d8
2 files changed