audio: Add some fall through comments

Static code analysers expect these comments for case statements without
a break statement.

Signed-off-by: Stefan Weil <sw@weilnetz.de>
Signed-off-by: malc <av1474@comtv.ru>

audio/audio.c

@@ -585,17 +585,20 @@ static int audio_pcm_info_eq (struct audio_pcm_info *info, struct audsettings *a
     switch (as->fmt) {
     case AUD_FMT_S8:
         sign = 1;
+        /* fall through */
     case AUD_FMT_U8:
         break;
 
     case AUD_FMT_S16:
         sign = 1;
+        /* fall through */
     case AUD_FMT_U16:
         bits = 16;
         break;
 
     case AUD_FMT_S32:
         sign = 1;
+        /* fall through */
     case AUD_FMT_U32:
         bits = 32;
         break;

audio/esdaudio.c

@@ -201,7 +201,7 @@ static int qesd_init_out (HWVoiceOut *hw, struct audsettings *as)
     case AUD_FMT_S32:
     case AUD_FMT_U32:
         dolog ("Will use 16 instead of 32 bit samples\n");
-
+        /* fall through */
     case AUD_FMT_S16:
     case AUD_FMT_U16:
     deffmt: