m68k: coldfire: return success for clk_enable(NULL)

The clk_enable is supposed work when CONFIG_HAVE_CLK is false, but it
returns -EINVAL. That means some drivers fail during probe.

[ 1.680000] flexcan: probe of flexcan.0 failed with error -22

Fixes: c1fb1bf64bb6 ("m68k: let clk_enable() return immediately if clk is NULL")
Fixes: bea8bcb12da0 ("m68knommu: Add support for the Coldfire m5441x.")
Signed-off-by: Dan Carpenter <[e-mail]>
Acked-by: Marc Kleine-Budde <[e-mail]>
Signed-off-by: Greg Ungerer <[e-mail]>

arch/m68k/coldfire/clk.c

···
 	unsigned long flags;
 
 	if (!clk)
-		return -EINVAL;
+		return 0;
 
 	spin_lock_irqsave(&clk_lock, flags);
 	if ((clk->enabled++ == 0) && clk->clk_ops)