fs/resctrl: Fix double-add of pseudo-locked region's RMID to free list

In the Linux kernel, the following vulnerability has been resolved: fs/resctrl: Fix double-add of pseudo-locked region's RMID to free list A pseudo-locked group's RMID is freed when it is created. On unmount rmdir_all_sub() unconditionally frees all RMID of all groups, resulting in a double-free of the pseudo-locked group's RMID. The consequence of this is that the original free results in the pseudo-locked group's RMID being added to the rmid_free_lru linked list and the second free then attempts to add the same RMID entry to the rmid_free_lru again. Do not double-free a pseudo-locked group's RMID.