ceph: fix comment over ceph_drop_caps_for_unlink

It's not clear what AUTH_RDCACHE means in this context, and we're
clearly just dropping LINK caps here.
Signed-off-by: Jeff Layton <jlayton@kernel.org>
Reviewed-by: "Yan, Zheng" <zyan@redhat.com>
Signed-off-by: Ilya Dryomov <idryomov@gmail.com>

fs/ceph/caps.c

@@ -4096,7 +4096,7 @@ void ceph_put_fmode(struct ceph_inode_info *ci, int fmode)
 }
 
 /*
- * For a soon-to-be unlinked file, drop the AUTH_RDCACHE caps. If it
+ * For a soon-to-be unlinked file, drop the LINK caps. If it
  * looks like the link count will hit 0, drop any other caps (other
  * than PIN) we don't specifically want (due to the file still being
  * open).