ASoC: core - Optimise and refactor pcm_new() to pass only rtd

Currently pcm_new() passes in 3 arguments :- card, pcm and DAI.

Refactor this to only pass in 1 argument (i.e. the rtd) since struct rtd contains
card, pcm and DAI along with other members too that are useful too.

Signed-off-by: Liam Girdwood <lrg@ti.com>
Signed-off-by: Mark Brown <broonie@opensource.wolfsonmicro.com>