ALSA: es1688: Drop superfluous ioctl PCM ops

snd_es1688_ioctl() does nothing but calling the default handler.
Now PCM core accepts NULL as the default ioctl ops(*), so let's drop
altogether.

(*) commit fc033cbf ("ALSA: pcm: Allow NULL ioctl ops")

Link: https://lore.kernel.org/r/20191210061145.24641-7-tiwai@suse.deSigned-off-by: Takashi Iwai <tiwai@suse.de>

sound/isa/es1688/es1688_lib.c

@@ -309,12 +309,6 @@ static void snd_es1688_set_rate(struct snd_es1688 *chip, struct snd_pcm_substrea
 	snd_es1688_write(chip, 0xa2, divider);
 }
 
-static int snd_es1688_ioctl(struct snd_pcm_substream *substream,
-			    unsigned int cmd, void *arg)
-{
-	return snd_pcm_lib_ioctl(substream, cmd, arg);
-}
-
 static int snd_es1688_trigger(struct snd_es1688 *chip, int cmd, unsigned char value)
 {
 	int val;
@@ -681,7 +675,6 @@ int snd_es1688_create(struct snd_card *card,
 static const struct snd_pcm_ops snd_es1688_playback_ops = {
 	.open =			snd_es1688_playback_open,
 	.close =		snd_es1688_playback_close,
-	.ioctl =		snd_es1688_ioctl,
 	.prepare =		snd_es1688_playback_prepare,
 	.trigger =		snd_es1688_playback_trigger,
 	.pointer =		snd_es1688_playback_pointer,
@@ -690,7 +683,6 @@ static const struct snd_pcm_ops snd_es1688_playback_ops = {
 static const struct snd_pcm_ops snd_es1688_capture_ops = {
 	.open =			snd_es1688_capture_open,
 	.close =		snd_es1688_capture_close,
-	.ioctl =		snd_es1688_ioctl,
 	.prepare =		snd_es1688_capture_prepare,
 	.trigger =		snd_es1688_capture_trigger,
 	.pointer =		snd_es1688_capture_pointer,