hwmon: fix a NULL vs IS_ERR_OR_NULL() check in xgene_hwmon_probe()

The devm_memremap() function returns error pointers on error,
it doesn't return NULL.

Fixes: c7cefce ("hwmon: (xgene) access mailbox as RAM")
Signed-off-by: Xinghuo Chen <xinghuo.chen@foxmail.com>
Link: https://lore.kernel.org/r/tencent_9AD8E7683EC29CAC97496B44F3F865BA070A@qq.com
Signed-off-by: Guenter Roeck <linux@roeck-us.net>

Author: Xinghuo Chen

drivers/hwmon/xgene-hwmon.c

@@ -706,7 +706,7 @@ static int xgene_hwmon_probe(struct platform_device *pdev)
 			goto out;
 		}
 
-		if (!ctx->pcc_comm_addr) {
+		if (IS_ERR_OR_NULL(ctx->pcc_comm_addr)) {
 			dev_err(&pdev->dev,
 				"Failed to ioremap PCC comm region\n");
 			rc = -ENOMEM;