[OpenMP] Fix defaultmap(firstprivate:pointer) handling (#169622)
This fixes a bug where pointers from defaultmap(firstprivate:pointer)
were incorrectly treated as firstprivate literals, causing
OMP_MAP_LITERAL to be set. This prevented the runtime from performing
device address lookup.
Realted PR https://github.com/llvm/llvm-project/pull/167879
Co-authored-by: Sairudra More <moresair@pe31.hpc.amslabs.hpecorp.net>