[PATCH] ASoC: soc-component: improve error reporting for register access

[Pierre-Louis Bossart]

>> BTW while looking at the code, I started to wonder if it's intentional
>> that we cannot check any error code on component->driver->read(). We do
>> for the write and on regmap read, which suggests this API is problematic?
> 
> I dunno about intentional but it's always been that way since ASoC was
> originally merged, it's just that nobody's ever changed that as part of
> one of the refactorings.  I did add error checking to the regmap read
> interface when I wrote that but I wasn't about to go fixing up all the
> ASoC drivers for a new API.

I started looking, there aren't that many users of that callback, but
some of the tlv320dac33 and twl6040 drivers would need a lot of changes.
that's probably going to be legacy code at this point.