ALSA: pcm: Correct PCM BUG error message

While converting to dev_*(), the message showing the invalid PCM
position was wrongly tagged as if an XRUN although it's actually a
BUG.  This patch corrects the message again.

Signed-off-by: Takashi Iwai <tiwai@suse.de>
diff --git a/sound/core/pcm_lib.c b/sound/core/pcm_lib.c
index dfc2854..7b9e2fb 100644
--- a/sound/core/pcm_lib.c
+++ b/sound/core/pcm_lib.c
@@ -345,7 +345,7 @@
 			snd_pcm_debug_name(substream, name, sizeof(name));
 			xrun_log_show(substream);
 			pcm_err(substream->pcm,
-				"XRUN: %s, pos = %ld, buffer size = %ld, period size = %ld\n",
+				"BUG: %s, pos = %ld, buffer size = %ld, period size = %ld\n",
 				name, pos, runtime->buffer_size,
 				runtime->period_size);
 		}