mfd: arizona: Remove BUG_ON usage

BUG_ON macros are generally frowned upon when the issue isn't super
critical, the kernel can certainly carry on with the 32k clock on the
CODEC in a bad state so change the BUG_ON to a WARN_ON.
Signed-off-by: Charles Keepax <ckeepax@opensource.cirrus.com>
Signed-off-by: Lee Jones <lee.jones@linaro.org>

drivers/mfd/arizona-core.c

@@ -80,7 +80,7 @@ int arizona_clk32k_disable(struct arizona *arizona)
 {
 	mutex_lock(&arizona->clk_lock);
 
-	BUG_ON(arizona->clk32k_ref <= 0);
+	WARN_ON(arizona->clk32k_ref <= 0);
 
 	arizona->clk32k_ref--;