Testbench: Add pipeline trigger stop to test end

This patch adds the missing call to end of test run. It prevents
the pipeline reset to print error traces about illegal state
change.

Signed-off-by: Seppo Ingalsuo <seppo.ingalsuo@linux.intel.com>

tools/testbench/testbench.c

@@ -259,6 +259,7 @@ int main(int argc, char **argv)
 	/* reset and free pipeline */
 	toc = clock();
 	tb_enable_trace(true);
+	pipeline_trigger(p, cd, COMP_TRIGGER_STOP);
 	ret = pipeline_reset(p, cd);
 	if (ret < 0) {
 		fprintf(stderr, "error: pipeline reset\n");