ALSA: hda - Add a warning if pending IRQ is found

The pending IRQ handling is a very hackish workaround and should be
avoided as much as possible via a larger bdl_pos_adj option value.
Put a warning message if this situation occurs so that the user may have
a chance to notice that something is wrong.

Signed-off-by: Takashi Iwai <tiwai@suse.de>
Signed-off-by: Jaroslav Kysela <perex@perex.cz>