ASoC: Add delay information for Samsung IISv2 DAIs

Report the current FIFO depth when delay is queried. The FIFO is only
16 frames deep so the latency will be at most a couple of miliseconds
(and we tend to end up reporting zero most of the time) but it may
help some applications.

Signed-off-by: Mark Brown <broonie@opensource.wolfsonmicro.com>
Acked-by: Liam Girdwood <lrg@slimlogic.co.uk>