core: add option to suppress error logging if nm_utils_modprobe() fails

We don't want error logging for nm_platform_link_add() which
tries to load the bonding module. Later we will run tests as non-root,
where modprobe will fail. Logging an error would break the tests.

src/platform/nm-linux-platform.c

@@ -2439,7 +2439,7 @@ link_add (NMPlatform *platform,
 		 * bond0 automatically.
 		 */
 		if (!g_file_test ("/sys/class/net/bonding_masters", G_FILE_TEST_EXISTS))
-			nm_utils_modprobe (NULL, "bonding", "max_bonds=0", NULL);
+			nm_utils_modprobe (NULL, TRUE, "bonding", "max_bonds=0", NULL);
 	}
 
 	debug ("link: add link '%s' of type '%s' (%d)",