video: use kobj_to_dev()

Use kobj_to_dev() instead of container_of()
Signed-off-by: Wang Qing <wangqing@vivo.com>
Signed-off-by: Sam Ravnborg <sam@ravnborg.org>
Link: https://patchwork.freedesktop.org/patch/msgid/1600776867-24226-1-git-send-email-wangqing@vivo.com

drivers/video/fbdev/aty/radeon_base.c

@@ -2200,7 +2200,7 @@ static ssize_t radeon_show_edid1(struct file *filp, struct kobject *kobj,
 				 struct bin_attribute *bin_attr,
 				 char *buf, loff_t off, size_t count)
 {
-	struct device *dev = container_of(kobj, struct device, kobj);
+	struct device *dev = kobj_to_dev(kobj);
 	struct fb_info *info = dev_get_drvdata(dev);
         struct radeonfb_info *rinfo = info->par;
 
@@ -2212,7 +2212,7 @@ static ssize_t radeon_show_edid2(struct file *filp, struct kobject *kobj,
 				 struct bin_attribute *bin_attr,
 				 char *buf, loff_t off, size_t count)
 {
-	struct device *dev = container_of(kobj, struct device, kobj);
+	struct device *dev = kobj_to_dev(kobj);
 	struct fb_info *info = dev_get_drvdata(dev);
         struct radeonfb_info *rinfo = info->par;