ALSA: Optimize module name check

module->name is a fixed array, so we can check the empty contents
straightforwardly in module_slot_match().

Spotted by coverity CID 1056786.

Signed-off-by: Takashi Iwai <tiwai@suse.de>
diff --git a/sound/core/init.c b/sound/core/init.c
index 6b90871..01a8938 100644
--- a/sound/core/init.c
+++ b/sound/core/init.c
@@ -66,7 +66,7 @@
 #ifdef MODULE
 	const char *s1, *s2;
 
-	if (!module || !module->name || !slots[idx])
+	if (!module || !*module->name || !slots[idx])
 		return 0;
 
 	s1 = module->name;