ASoC: Fix burstsize and DSP_B format problems in imx-ssi.

When choosing IMX_DMA flag, burtsizes are set to its default
value (0) which leads to driver malfunction. Change them to 4.

DSP_B interface needs additional flag to match DSP_B formats
as described in several codecs as wm8741 and aic3205.

Signed-off-by: Javier Martin <javier.martin@vista-silicon.com>
Acked-by: Liam Girdwood <lrg@slimlogic.co.uk>
Signed-off-by: Mark Brown <broonie@opensource.wolfsonmicro.com>