clk: aspeed: Fix return value check in aspeed_cc_init()

In case of error, the function of_iomap() returns NULL pointer not
ERR_PTR(). The IS_ERR() test in the return value check should be
replaced with NULL test.

Fixes: a2e230c7b2ea ("clk: Add clock driver for ASPEED BMC SoCs")
Signed-off-by: Wei Yongjun <weiyongjun1@huawei.com>
Signed-off-by: Stephen Boyd <sboyd@codeaurora.org>

drivers/clk/clk-aspeed.c

@@ -609,7 +609,7 @@ static void __init aspeed_cc_init(struct device_node *np)
 	int i;
 
 	scu_base = of_iomap(np, 0);
-	if (IS_ERR(scu_base))
+	if (!scu_base)
 		return;
 
 	aspeed_clk_data = kzalloc(sizeof(*aspeed_clk_data) +