Following are present in mach-netx/fb.c:

[snip]

struct clk *clk_get(struct device *dev, const char *id)
{
	return dev && strcmp(dev_name(dev), "fb") == 0 ? NULL : ERR_PTR(-ENOENT);
}

I can remove first four without any issues, but just can't remove the last one.
The dummy clk_get() always returns NULL, whereas this one returns NULL only for
fb device.

How should I fix this?

Another thing I'm not sure is that the typical clk_get() callers only
tests IS_ERR() on the returned value. As a clk newbie, I don't know
whether there will be lots of clk users seeing this (new) NULL value
on !CONFIG_HAVE_CLK and whether the current behavior is correct..

Thanks,
Fengguang