ALSA: hda - Fix missing static inline to beep dummy function

The commit 2308f4add3 missed static inline
thus it resulted in multiple-definitions error at linking.

Signed-off-by: Takashi Iwai <tiwai@suse.de>

sound/pci/hda/hda_beep.h

@@ -54,7 +54,7 @@ static inline int snd_hda_attach_beep_device(struct hda_codec *codec, int nid)
 {
 	return 0;
 }
-void snd_hda_detach_beep_device(struct hda_codec *codec)
+static inline void snd_hda_detach_beep_device(struct hda_codec *codec)
 {
 }
 #endif