Free the 'sioc' when the qio_channel_socket_connect_sync() fails.

Reported-by: Euler Robot <euler.robot@huawei.com>
Signed-off-by: Alex Chen <alex.chen@huawei.com>
Reviewed-by: Li Qiang <liq3ea@gmail.com>
Reviewed-by: Laurent Vivier <laurent@vivier.eu>
Message-Id: <20201126065702.35095-1-alex.chen@huawei.com>
Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>