[ALSA] snd-hda-intel: Improve azx_position_ok()

Add back the zero return value (activate workqueue) when
bdl_pos_adj is nonzero for position check.

Do the position related check only for first next period
using wallclk counter.

Return -1 value (ignore interrupt) when period_bytes
variable is zero.

Signed-off-by: Jaroslav Kysela <perex@perex.cz>