rpcrdma: Always release the rpcrdma_device's xa_array

Dai pointed out that the xa_init_flags() in rpcrdma_add_one() needs
to have a matching xa_destroy() in rpcrdma_remove_one() to release
underlying memory that the xarray might have accrued during
operation.

Reported-by: Dai Ngo <dai.ngo@oracle.com>
Fixes: 7e86845 ("rpcrdma: Implement generic device removal")
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>

net/sunrpc/xprtrdma/ib_client.c

@@ -153,6 +153,7 @@ static void rpcrdma_remove_one(struct ib_device *device,
 	}
 
 	trace_rpcrdma_client_remove_one_done(device);
+	xa_destroy(&rd->rd_xa);
 	kfree(rd);
 }