devfreq/exynos-bus: Use common error handling code in exynos_bus_target()

[SF Markus Elfring]

> As I already commented on your other patch related to extcon-max14577,
> this patch might remove the redundant error message.

I hope that more software improvements can be achieved in this design direction.


> But, it makes the code more complicated in side of readability. I prefer existing code.

I prefer to avoid duplicated code a bit more.

Regards,
Markus