pds_core: fix auxiliary device add/del races

In the Linux kernel, the following vulnerability has been resolved: pds_core: fix auxiliary device add/del races Two paths add or delete the same slot (pf->vfs[vf_id].padev): a VF's pdsc_reset_done() and the PF's devlink enable_vnet/disable_vnet handler. They serialize on config_lock, but neither guards the slot under it correctly. add() registers and stores a new auxiliary device without first checking the slot, so a second add of an already-populated slot leaks the first device. del() makes that check outside config_lock, so two concurrent dels can both pass it; the first clears the slot, and the second dereferences a NULL pointer. Check and update the slot under config_lock in both paths.