xen/netback: fix error path of xenvif_connect_data()

BugLink: https://bugs.launchpad.net/bugs/1850454

commit 3d5c1a03 upstream.

xenvif_connect_data() calls module_put() in case of error. This is
wrong as there is no related module_get().

Remove the superfluous module_put().

Fixes: 279f438e ("xen-netback: Don't destroy the netdev until the vif is shut down")
Cc: <stable@vger.kernel.org> # 3.12
Signed-off-by: Juergen Gross <jgross@suse.com>
Reviewed-by: Paul Durrant <paul@xen.org>
Reviewed-by: Wei Liu <wei.liu@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Connor Kuehl <connor.kuehl@canonical.com>
Signed-off-by: Kleber Sacilotto de Souza <kleber.souza@canonical.com>

drivers/net/xen-netback/interface.c

@@ -620,7 +620,6 @@ int xenvif_connect(struct xenvif_queue *queue, unsigned long tx_ring_ref,
 err_unmap:
 	xenvif_unmap_frontend_rings(queue);
 err:
-	module_put(THIS_MODULE);
 	return err;
 }