PM / devfreq: Check governor before using governor->name

Commit 96ffcdf ("PM / devfreq: Remove redundant governor_name from
struct devfreq") removes governor_name and uses governor->name to replace
it. But devfreq->governor may be NULL and directly using
devfreq->governor->name may cause null pointer exception. Move the check of
governor to before using governor->name.

Fixes: 96ffcdf ("PM / devfreq: Remove redundant governor_name from struct devfreq")
Signed-off-by: Lifeng Zheng <zhenglifeng1@huawei.com>
Link: https://lore.kernel.org/lkml/20250421030020.3108405-5-zhenglifeng1@huawei.com/
Signed-off-by: Chanwoo Choi <cw00.choi@samsung.com>

Author: Lifeng Zheng

drivers/devfreq/devfreq.c

@@ -1376,15 +1376,11 @@ int devfreq_remove_governor(struct devfreq_governor *governor)
 		int ret;
 		struct device *dev = devfreq->dev.parent;
 
+		if (!devfreq->governor)
+			continue;
+
 		if (!strncmp(devfreq->governor->name, governor->name,
 			     DEVFREQ_NAME_LEN)) {
-			/* we should have a devfreq governor! */
-			if (!devfreq->governor) {
-				dev_warn(dev, "%s: Governor %s NOT present\n",
-					 __func__, governor->name);
-				continue;
-				/* Fall through */
-			}
 			ret = devfreq->governor->event_handler(devfreq,
 						DEVFREQ_GOV_STOP, NULL);
 			if (ret) {