staging: greybus: audio_topology: Fix spaces between operator and string

Fix coding style issue caught by checkpatch.pl related to the following
warning:
	- "CHECK: spaces preferred around that '*' (ctx:VxV) "
Signed-off-by: Emmanuil Chatzipetru <chatzi.emanuel@gmail.com>
Acked-by: Johan Hovold <johan@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/staging/greybus/audio_topology.c

@@ -1312,7 +1312,7 @@ static int gbaudio_tplg_process_routes(struct gbaudio_module_info *module,
 			goto error;
 		}
 		dev_dbg(module->dev, "Route {%s, %s, %s}\n", dapm_routes->sink,
-			(dapm_routes->control) ? dapm_routes->control:"NULL",
+			(dapm_routes->control) ? dapm_routes->control : "NULL",
 			dapm_routes->source);
 		dapm_routes++;
 		curr++;