ALSA: hda - Move prepared flag into struct hdac_stream

This flag seems used commonly, so deserves to be located there.

Signed-off-by: Takashi Iwai <tiwai@suse.de>
diff --git a/include/sound/hdaudio.h b/include/sound/hdaudio.h
index 15bc039..dbeb195 100644
--- a/include/sound/hdaudio.h
+++ b/include/sound/hdaudio.h
@@ -390,6 +390,7 @@
 
 	bool opened:1;
 	bool running:1;
+	bool prepared:1;
 	bool no_period_wakeup:1;
 	bool locked:1;