Summary: The NVPTX backend optimizes the ABI for functions that are internal, however, this is not legal for indirect call prototypes. Previously, we would modify the ABI on an aggregate byval type passed to an indirect call prototype, which would make PTXAS error. This patch just passes the function as a nullptr to force strict ABI compliance without modification in the helper function. Fixes https://github.com/llvm/llvm-project/issues/100055 (cherry picked from commit e0649a5dfc6b859d652318f578bc3d49674787a4)