ALSA: Add extra delay count in PCM

Added runtime->delay field to adjust the delayed samples for snd_pcm_delay().
Typically a hardware FIFO length is stored in this field, so that the
extra delay between hwptr and applptr can be computed.

Signed-off-by: Takashi Iwai <tiwai@suse.de>

include/sound/pcm.h

@@ -270,6 +270,7 @@ struct snd_pcm_runtime {
 	snd_pcm_uframes_t hw_ptr_base;	/* Position at buffer restart */
 	snd_pcm_uframes_t hw_ptr_interrupt; /* Position at interrupt time */
 	unsigned long hw_ptr_jiffies;	/* Time when hw_ptr is updated */
+	snd_pcm_sframes_t delay;	/* extra delay; typically FIFO size */
 
 	/* -- HW params -- */
 	snd_pcm_access_t access;	/* access mode */