afs: Fix the volume AFS_VOLUME_RM_TREE is set on

afs: Fix the volume AFS_VOLUME_RM_TREE is set on

Fix afs_insert_volume_into_cell() to set AFS_VOLUME_RM_TREE on the volume
replaced, not the new volume, as it's now removed from the cell's volume
tree.  This will cause the old volume to be removed from the tree twice and
the new volume never to be removed.

Fixes: 9a6b294ab496 ("afs: Fix use-after-free due to get/remove race in volume tree")
Closes: https://sashiko.dev/#/patchset/20260618074903.2374756-1-dhowells%40redhat.com
Signed-off-by: David Howells <dhowells@redhat.com>
Link: https://patch.msgid.link/20260622090856.2746629-21-dhowells@redhat.com
cc: Marc Dionne <marc.dionne@auristor.com>
cc: linux-afs@lists.infradead.org
Signed-off-by: Christian Brauner (Amutable) <brauner@kernel.org>