ASoC: soc-component: merge soc_pcm_trigger_start/stop()

Now, soc_pcm_trigger_start/stop() are simple enough.
Let's merge these into soc_pcm_trigger().

Signed-off-by: Kuninori Morimoto <kuninori.morimoto.gx@renesas.com>
Reviewed-by: Ranjani Sridharan <ranjani.sridharan@linux.intel.com>
Link: https://lore.kernel.org/r/87ftbbw8wj.wl-kuninori.morimoto.gx@renesas.com


Signed-off-by: Mark Brown <broonie@kernel.org>