scsi: mpi3mr: Fix expander node leak in mpi3mr_remove()

Add a missing resource clean up in .remove.

Fixes: e22bae30

 ("scsi: mpi3mr: Add expander devices to STL")
Signed-off-by: Tomas Henzl <thenzl@redhat.com>
Link: https://lore.kernel.org/r/20230302234336.25456-7-thenzl@redhat.com
Acked-by: Sathya Prakash Veerichetty <sathya.prakash@broadcom.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>