clk: at91: fix check of clk_register() returned value

The clk_register() function returns a valid pointer to struct clk or
ERR_PTR() error code, this makes a check for returned NULL value
useless and may lead to oops on error path.

Signed-off-by: Vladimir Zapolskiy <vz@mleia.com>
Acked-by: Alexandre Belloni <alexandre.belloni@free-electrons.com>
Acked-by: Boris Brezillon <boris.brezillon@free-electrons.com>
Fixes: bcc5fd49a0fd ("clk: at91: add a driver for the h32mx clock")
Signed-off-by: Stephen Boyd <sboyd@codeaurora.org>

drivers/clk/at91/clk-h32mx.c

@@ -114,7 +114,7 @@ static void __init of_sama5d4_clk_h32mx_setup(struct device_node *np)
 	h32mxclk->regmap = regmap;
 
 	clk = clk_register(NULL, &h32mxclk->hw);
-	if (!clk) {
+	if (IS_ERR(clk)) {
 		kfree(h32mxclk);
 		return;
 	}