ASoC: fix W=1 build warnings

We get 1 warning about global functions without a declaration
in the ASoC sub-system when building with W=1:

sound/soc/sh/rcar/core.c:113:6: warning: no previous prototype for 'rsnd_mod_make_sure' [-Wmissing-prototypes]
 void rsnd_mod_make_sure(struct rsnd_mod *mod, enum rsnd_mod_type type)

In this case, the function 'rsnd_mod_make_sure' is declared in rsnd.h file,
but it only valid if the macro DEBUG is claimed.

so the implementation of function 'rsnd_mod_make_sure' need be
held by macro DEBUG.
Signed-off-by: Baoyou Xie <baoyou.xie@linaro.org>
Signed-off-by: Mark Brown <broonie@kernel.org>

sound/soc/sh/rcar/core.c

@@ -110,6 +110,7 @@ MODULE_DEVICE_TABLE(of, rsnd_of_match);
 /*
  *	rsnd_mod functions
  */
+#ifdef DEBUG
 void rsnd_mod_make_sure(struct rsnd_mod *mod, enum rsnd_mod_type type)
 {
 	if (mod->type != type) {
@@ -120,6 +121,7 @@ void rsnd_mod_make_sure(struct rsnd_mod *mod, enum rsnd_mod_type type)
 			 rsnd_mod_name(mod), rsnd_mod_id(mod));
 	}
 }
+#endif
 
 char *rsnd_mod_name(struct rsnd_mod *mod)
 {