ASoC: SOF: i.MX: simplify Kconfig

[plbossart]

Follow the Intel example and simplify the Kconfig
a) start from the end-product and use snd-sof-of as a helper
b) use 'depends on' to filter out configurations.

Signed-off-by: Pierre-Louis Bossart pierre-louis.bossart@linux.intel.com

[plbossart]

@dbaluta this is inspired by the changes that we made on the Intel side based on @arndb's feedback. Much better to consider snd-sof-of as a helper and start the user selection at the product level.

[dbaluta]

@plbossart i think this code is more clear. On the other hand saying that snd-sof-of is a 'helper' doesn't make much sense in my understanding.

snd-sof-of is the starting point for the OF platform driver:

sound/soc/sof/sof-of-dev.c

/* DT driver definition */
static struct platform_driver snd_sof_of_driver = {
»       .probe = sof_of_probe,
»       .remove = sof_of_remove, 
»       .driver = {
»       »       .name = "sof-audio-of",
»       »       .pm = &sof_of_pm,
»       »       .of_match_table = sof_of_ids,
»       },
};
module_platform_driver(snd_sof_of_driver);

[plbossart]

it's not a pure library indeed, but the point is that sof-of-dev is at the end of the 'select' clauses, it does not select anything on its own. Maybe 'common module' is a better wording.