slimbus: stream: add checks for invalid unprepare/disable usage

slim_disable_stream() and slim_stream_unprepare() are exported, so add
sanity checks preventing unmatched/invalid calls.

Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Signed-off-by: Srinivas Kandagatla <srinivas.kandagatla@linaro.org>
Link: https://lore.kernel.org/r/20221118065246.6835-6-srinivas.kandagatla@linaro.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/slimbus/stream.c

@@ -414,6 +414,9 @@ int slim_stream_disable(struct slim_stream_runtime *stream)
 	struct slim_controller *ctrl = stream->dev->ctrl;
 	int ret, i;
 
+	if (!stream->ports || !stream->num_ports)
+		return -EINVAL;
+
 	if (ctrl->disable_stream)
 		ctrl->disable_stream(stream);
 
@@ -445,6 +448,9 @@ int slim_stream_unprepare(struct slim_stream_runtime *stream)
 {
 	int i;
 
+	if (!stream->ports || !stream->num_ports)
+		return -EINVAL;
+
 	for (i = 0; i < stream->num_ports; i++)
 		slim_disconnect_port(stream, &stream->ports[i]);