GPGPU: Test scalar parameters of type half/float/double/fp128/x86_fp80/ppc_fp128

We currently only test that the code structure we generate for these scalar
parameters is correct and we add these types to make sure later code generation
additions have sufficient test coverage.

In case some of these types cannot be mapped due to missing hardware support
on the GPU some of these test cases may need to be updated later on.

llvm-svn: 275548