tests: fix e1000-test leak

Spotted by ASAN.
Signed-off-by: NMarc-André Lureau <marcandre.lureau@redhat.com>
Reviewed-by: NPhilippe Mathieu-Daudé <f4bug@amsat.org>

tests/e1000-test.c

@@ -44,6 +44,7 @@ int main(int argc, char **argv)
 
         path = g_strdup_printf("e1000/%s", models[i]);
         qtest_add_data_func(path, models[i], test_device);
+        g_free(path);
     }
 
     return g_test_run();