[CUDA] Do not embed a fatbinary when using the new driver

Previously, when using the new driver we created a fatbinary with the
PTX and Cubin output. This was mainly done in an attempt to create some
backwards compatibility with the existing CUDA support that embeds the
fatbinary in each TU. This will most likely be more work than necessary
to actually implement. The linker wrapper cannot do anything with these
embedded PTX files because we do not know how to link them, and if we
did want to include multiple files it should go through the
`clang-offload-packager` instead. Also this didn't repsect the setting
that disables embedding PTX (although it wasn't used anyway).

Reviewed By: tra

Differential Revision: https://reviews.llvm.org/D128441