Many HD-audio controllers seem inaccurate about the IRQ timing of
PCM period updates.  This has caused problems on audio quality; e.g.
JACK doesn't work with two periods.

This patch fixes the problem by checking the current DMA position
at IRQ handler and delays the period-update via a workq if it's
inaccurate.
Signed-off-by: Takashi Iwai <tiwai@suse.de>
Signed-off-by: Jaroslav Kysela <perex@perex.cz>