ASoC: soc-core: do rtd->id trick at snd_soc_add_pcm_runtime()

ASoC: soc-core: do rtd->id trick at snd_soc_add_pcm_runtime()

qcom/qdsp6 want to use irregular rtd->id because of its topology.
Current code is calculating it at soc_init_pcm_runtime() which calls
soc_new_pcm(), and it doesn't save it to rtd->id.

Let's calculate and save it to rtd at snd_soc_add_pcm_runtime()
which create rtd and connect related components.

But, this feature should be implemented by using "dai_link" instead
of "component". Add FIXME as comment.

Signed-off-by: Kuninori Morimoto <kuninori.morimoto.gx@renesas.com>
Link: https://patch.msgid.link/87r086b84w.wl-kuninori.morimoto.gx@renesas.com
Signed-off-by: Mark Brown <broonie@kernel.org>