quoted

As Florian pointed out, the clk_ API is happy to take a NULL pointer
for a clock. So you don't need this last else.

    Andrew

I do return with an error from the probe if the clk_prepare_enable() fails,
so I was calling the prepare with a valid clock.

How many times do we need to say it?

NULL is a valid clock. 

int clk_prepare(struct clk *clk)
{
	if (!clk)
	   return 0;

	   return clk_core_prepare_lock(clk->core);
}

int clk_enable(struct clk *clk)
{
	if (!clk)
	   return 0;

	   return clk_core_enable_lock(clk->core);
}

clk_prepare_enable(NULL) returns 0, which is not an error.

	 Andrew