imx: WARN in clk_disable if the clock isn't enabled

Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Cc: Sascha Hauer <kernel@pengutronix.de>
Cc: Russell King <linux@arm.linux.org.uk>

arch/arm/plat-mxc/clock.c

@@ -56,6 +56,7 @@ static void __clk_disable(struct clk *clk)
 	__clk_disable(clk->parent);
 	__clk_disable(clk->secondary);
 
+	WARN_ON(!clk->usecount);
 	if (!(--clk->usecount) && clk->disable)
 		clk->disable(clk);
 }