ALSA: ua101: Convert to the common vmalloc memalloc

The recent change (*) in the ALSA memalloc core allows us to drop the
special vmalloc-specific allocation and page handling.  This patch
coverts to the common code.
(*) 1fe7f397: ALSA: memalloc: Add vmalloc buffer allocation
                  support
    7e8edae3: ALSA: pcm: Handle special page mapping in the
                  default mmap handler

Link: https://lore.kernel.org/r/20191105151856.10785-15-tiwai@suse.deSigned-off-by: Takashi Iwai <tiwai@suse.de>

sound/usb/misc/ua101.c

@@ -733,7 +733,7 @@ static int capture_pcm_hw_params(struct snd_pcm_substream *substream,
 	if (err < 0)
 		return err;
 
-	return snd_pcm_lib_alloc_vmalloc_buffer(substream,
+	return snd_pcm_lib_malloc_pages(substream,
 					params_buffer_bytes(hw_params));
 }
 
@@ -751,13 +751,13 @@ static int playback_pcm_hw_params(struct snd_pcm_substream *substream,
 	if (err < 0)
 		return err;
 
-	return snd_pcm_lib_alloc_vmalloc_buffer(substream,
+	return snd_pcm_lib_malloc_pages(substream,
 					params_buffer_bytes(hw_params));
 }
 
 static int ua101_pcm_hw_free(struct snd_pcm_substream *substream)
 {
-	return snd_pcm_lib_free_vmalloc_buffer(substream);
+	return snd_pcm_lib_free_pages(substream);
 }
 
 static int capture_pcm_prepare(struct snd_pcm_substream *substream)
@@ -889,7 +889,6 @@ static const struct snd_pcm_ops capture_pcm_ops = {
 	.prepare = capture_pcm_prepare,
 	.trigger = capture_pcm_trigger,
 	.pointer = capture_pcm_pointer,
-	.page = snd_pcm_lib_get_vmalloc_page,
 };
 
 static const struct snd_pcm_ops playback_pcm_ops = {
@@ -901,7 +900,6 @@ static const struct snd_pcm_ops playback_pcm_ops = {
 	.prepare = playback_pcm_prepare,
 	.trigger = playback_pcm_trigger,
 	.pointer = playback_pcm_pointer,
-	.page = snd_pcm_lib_get_vmalloc_page,
 };
 
 static const struct uac_format_type_i_discrete_descriptor *
@@ -1296,6 +1294,8 @@ static int ua101_probe(struct usb_interface *interface,
 	strcpy(ua->pcm->name, name);
 	snd_pcm_set_ops(ua->pcm, SNDRV_PCM_STREAM_PLAYBACK, &playback_pcm_ops);
 	snd_pcm_set_ops(ua->pcm, SNDRV_PCM_STREAM_CAPTURE, &capture_pcm_ops);
+	snd_pcm_lib_preallocate_pages_for_all(ua->pcm, SNDRV_DMA_TYPE_VMALLOC,
+					      NULL, 0, 0);
 
 	err = snd_usbmidi_create(card, ua->intf[INTF_MIDI],
 				 &ua->midi_list, &midi_quirk);