IB/rxe: Fix a memory leak in rxe_qp_cleanup()

A socket is associated with every QP by the rxe driver but sock_release()
is never called. Add a call to sock_release() in rxe_qp_cleanup().

Fixes: commit 8700e3e7c48A5 ("Add Soft RoCE driver")
Signed-off-by: Bart Van Assche <bart.vanassche@sandisk.com>
Cc: Moni Shoua <monis@mellanox.com>
Cc: Kamal Heib <kamalh@mellanox.com>
Cc: Amir Vadai <amirv@mellanox.com>
Cc: Haggai Eran <haggaie@mellanox.com>
Cc: <stable@vger.kernel.org>
Reviewed-by: Moni Shoua <monis@mellanox.com>
Signed-off-by: Doug Ledford <dledford@redhat.com>

drivers/infiniband/sw/rxe/rxe_qp.c

@@ -853,4 +853,5 @@ void rxe_qp_cleanup(void *arg)
 	free_rd_atomic_resources(qp);
 
 	kernel_sock_shutdown(qp->sk, SHUT_RDWR);
+	sock_release(qp->sk);
 }