ASoC: rsnd: rsnd_mod_id() return -1 if mod was NULL

enabling to use same method for exception case is useful.
Signed-off-by: Kuninori Morimoto <kuninori.morimoto.gx@renesas.com>
Tested-by: Keita Kobayashi <keita.kobayashi.ym@renesas.com>
Signed-off-by: Mark Brown <broonie@kernel.org>

sound/soc/sh/rcar/rsnd.h

@@ -316,7 +316,7 @@ struct rsnd_mod {
 
 #define rsnd_mod_to_priv(mod) ((mod)->priv)
 #define rsnd_mod_to_dma(mod) (&(mod)->dma)
-#define rsnd_mod_id(mod) ((mod)->id)
+#define rsnd_mod_id(mod) ((mod) ? (mod)->id : -1)
 #define rsnd_mod_hw_start(mod)	clk_enable((mod)->clk)
 #define rsnd_mod_hw_stop(mod)	clk_disable((mod)->clk)