Adjust offsets for max load instruction offsets. This is more pessimistic

Adjust offsets for max load instruction offsets. This is more pessimistic
than it needs to be by 1 bit but I need to finish some other things so
that all the boundary cases will work in that situation. constpool.c
in test-suite will fail to assemble under our new internal test-suite sync
without this change.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@199343 91177308-0d34-0410-b5e6-96231b3b80d8