ALSA: pci: Drop superfluous snd_pcm_sgbuf_ops_page

snd_pcm_sgbuf_ops_page is no longer needed to be set explicitly to PCM
page ops since the recent change in the PCM core (*).  Leaving it NULL
should work as long as the preallocation has been done properly.

This patch drops the redundant lines.

(*) 7e8edae39f: ALSA: pcm: Handle special page mapping in the
                  default mmap handler

Link: https://lore.kernel.org/r/20191105151856.10785-19-tiwai@suse.de
Signed-off-by: Takashi Iwai <tiwai@suse.de>

sound/pci/via82xx_modem.c

@@ -801,7 +801,6 @@ static const struct snd_pcm_ops snd_via686_playback_ops = {
 	.prepare =	snd_via82xx_pcm_prepare,
 	.trigger =	snd_via82xx_pcm_trigger,
 	.pointer =	snd_via686_pcm_pointer,
-	.page =		snd_pcm_sgbuf_ops_page,
 };
 
 /* via686 capture callbacks */
@@ -814,7 +813,6 @@ static const struct snd_pcm_ops snd_via686_capture_ops = {
 	.prepare =	snd_via82xx_pcm_prepare,
 	.trigger =	snd_via82xx_pcm_trigger,
 	.pointer =	snd_via686_pcm_pointer,
-	.page =		snd_pcm_sgbuf_ops_page,
 };