ASoC: soc-pcm: remove soc_fill_silence()

No ALSA SoC driver has .fill_silence at component->driver->ops.
We can revive it if some-driver want to use it, but let's remove it
so far to avoid maintaining complex code
Signed-off-by: Kuninori Morimoto <kuninori.morimoto.gx@renesas.com>
Link: https://lore.kernel.org/r/87k1c55rof.wl-kuninori.morimoto.gx@renesas.comSigned-off-by: Mark Brown <broonie@kernel.org>

sound/soc/soc-pcm.c

@@ -2896,28 +2896,6 @@ static int soc_rtdcom_copy_user(struct snd_pcm_substream *substream, int channel
 	return -EINVAL;
 }
 
-static int soc_rtdcom_fill_silence(struct snd_pcm_substream *substream, int channel,
-				   unsigned long pos, unsigned long bytes)
-{
-	struct snd_soc_pcm_runtime *rtd = substream->private_data;
-	struct snd_soc_rtdcom_list *rtdcom;
-	struct snd_soc_component *component;
-
-	for_each_rtdcom(rtd, rtdcom) {
-		component = rtdcom->component;
-
-		if (!component->driver->ops ||
-		    !component->driver->ops->fill_silence)
-			continue;
-
-		/* FIXME. it returns 1st silence now */
-		return component->driver->ops->fill_silence(substream, channel,
-							    pos, bytes);
-	}
-
-	return -EINVAL;
-}
-
 static struct page *soc_rtdcom_page(struct snd_pcm_substream *substream,
 				    unsigned long offset)
 {
@@ -3089,8 +3067,6 @@ int soc_new_pcm(struct snd_soc_pcm_runtime *rtd, int num)
 
 		if (ops->copy_user)
 			rtd->ops.copy_user	= soc_rtdcom_copy_user;
-		if (ops->fill_silence)
-			rtd->ops.fill_silence	= soc_rtdcom_fill_silence;
 		if (ops->page)
 			rtd->ops.page		= soc_rtdcom_page;
 		if (ops->mmap)