clk: npcm7xx: fix return value check in npcm7xx_clk_init()

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

Fixes: fcfd1436 ("clk: npcm7xx: add clock controller")
Signed-off-by: Wei Yongjun <weiyongjun1@huawei.com>
Signed-off-by: Stephen Boyd <sboyd@kernel.org>

drivers/clk/clk-npcm7xx.c

@@ -555,7 +555,7 @@ static void __init npcm7xx_clk_init(struct device_node *clk_np)
 	}
 
 	clk_base = ioremap(res.start, resource_size(&res));
-	if (IS_ERR(clk_base))
+	if (!clk_base)
 		goto npcm7xx_init_error;
 
 	npcm7xx_clk_data = kzalloc(sizeof(*npcm7xx_clk_data->hws) *