[LangRef] Update saturating examples for llvm.smul.fix.sat. NFC
[LangRef] Update saturating examples for llvm.smul.fix.sat. NFC

Some saturation examples for llvm.smul.fix.sat were not showing
the correct result. I've adjusted the operands to make sure that
we actually trigger overflow in those examples.

git-svn-id: 0ff597fd157e6f4fc38580e8d64ab130330d2411@370566 91177308-0d34-0410-b5e6-96231b3b80d8

GPUOpen-Drivers/llvm,GPUOpen-Drivers/llvm,GPUOpen-Drivers/llvm,GPUOpen-Drivers/llvm,GPUOpen-Drivers/llvm,GPUOpen-Drivers/llvm,GPUOpen-Drivers/llvm,GPUOpen-Drivers/llvm