mpc512x/clock: fix clk_get logic

[Mark Brown]

On Fri, Oct 30, 2009 at 12:36:44PM +0100, Wolfram Sang wrote:
> On Fri, Oct 30, 2009 at 10:54:14AM +0000, Mark Brown wrote:

> > > - require the id field (as _this_ is the unique identifier)

> > NULL id fields are supposed to be supported in the cannonical clkdev
> > API, unfortunately.

> Hmm, ok, thanks for the hint. Where is this documented, I can't find it?

I'm not aware of any particular documentation on it but searching for
mailing list posts from rmk ought to turn up some posts on the issue.