Eliminate loads from the dispatch packet when they will have
a known value.
Also pattern match the code used by the library to handle partial
workgroup dispatches, which isn't necessary if reqd_work_group_size
is used.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@332771 91177308-0d34-0410-b5e6-96231b3b80d8
