[ALSA] Remove bogus check of mmap_count in snd_pcm_release()

Removed a bogus check of mmap_count in snd_pcm_release().
This is no longer true for the shared streams.

Signed-off-by: Takashi Iwai <tiwai@suse.de>
diff --git a/sound/core/pcm_native.c b/sound/core/pcm_native.c
index 9e49524..439f047 100644
--- a/sound/core/pcm_native.c
+++ b/sound/core/pcm_native.c
@@ -2205,7 +2205,6 @@
 	pcm_file = file->private_data;
 	substream = pcm_file->substream;
 	snd_assert(substream != NULL, return -ENXIO);
-	snd_assert(!atomic_read(&substream->mmap_count), );
 	pcm = substream->pcm;
 	fasync_helper(-1, file, 0, &substream->runtime->fasync);
 	mutex_lock(&pcm->open_mutex);