[OpenMP] Fix passing target id features to AMDGPU offloading (#94765)

Summary:
AMDGPU supports a `target-id` feature which is used to qualify targets
with different incompatible features. These are both rules and target
features. Currently, we pass `-target-cpu` twice when offloading to
OpenMP, and do not pass the target-id features at all. The effect was
that passing something like `--offload-arch=gfx90a:xnack+` would show up
as `-target-cpu=gfx90a:xnack+ -target-cpu=gfx90a`. Thus ignoring the
xnack completely and passing it twice. This patch fixes that to pass it
once and then separate it like how HIP does.