[OpenMP] Fix file arguments for embedding bitcode in the linker wrapper

Summary:
The linker wrapper supports embedding bitcode images instead of linked
device images to facilitate JIT in the device runtime. However, we were
incorrectly passing in the file twice when this option was set. This
patch makes sure we only use the intermediate result of the LTO pass and
don't add the final output to the full job.

In the future we will want to add both of these andle handle that
accoridngly to allow the runtime to either use the AoT compiled version
or JIT compile the bitcode version if availible.