ASoC: simple-card: simplify code

This patch set simplifies the code and make easier a possible multi-DAI links extension.
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v2:
- split the changes into 8 patches (Mark Brown request)
- remove the dynamic DAI link array allocation
- fix lack of init function when DT use

Ken ar c'hentañ	|	      ** Breizh ha Linux atav! **
Jef		|		http://moinejf.free.fr/

Just as a general thing about this and the other simple-card patches that are floating around: there's a lot of them all working on the same things. It'd be good to see more peer review and testing going on, mostly there's no comments from other people working on the code.