clk: imx: scu: Use common error handling code in __imx_clk_gpr_scu()

[Markus Elfring]

>> Use another label so that a bit of exception handling can be better reused
>> at the end of this function.
>
> Please don't send patches as reply to other(s) patches.

This is a general possibility to connect an information sources with
a corresponding change idea.
Will the acceptance grow for the presented source code transformation?

Regards,
Markus