drm/sysfs: Convert sysfs sprintf/snprintf family to sysfs_emit

Fix the following coccicheck warning:
drivers/gpu/drm/drm_sysfs.c:172:8-16: WARNING: use scnprintf or sprintf
drivers/gpu/drm/drm_sysfs.c:185:8-16: WARNING: use scnprintf or sprintf
drivers/gpu/drm/drm_sysfs.c:159:8-16: WARNING: use scnprintf or sprintf
Signed-off-by: Tian Tao <tiantao6@hisilicon.com>
Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Link: https://patchwork.freedesktop.org/patch/msgid/1616375978-12151-1-git-send-email-tiantao6@hisilicon.com

drivers/gpu/drm/drm_sysfs.c

@@ -156,7 +156,7 @@ static ssize_t status_show(struct device *device,
 
 	status = READ_ONCE(connector->status);
 
-	return snprintf(buf, PAGE_SIZE, "%s\n",
+	return sysfs_emit(buf, "%s\n",
 			  drm_get_connector_status_name(status));
 }
 
@@ -169,8 +169,7 @@ static ssize_t dpms_show(struct device *device,
 
 	dpms = READ_ONCE(connector->dpms);
 
-	return snprintf(buf, PAGE_SIZE, "%s\n",
-			drm_get_dpms_name(dpms));
+	return sysfs_emit(buf, "%s\n", drm_get_dpms_name(dpms));
 }
 
 static ssize_t enabled_show(struct device *device,
@@ -182,7 +181,7 @@ static ssize_t enabled_show(struct device *device,
 
 	enabled = READ_ONCE(connector->encoder);
 
-	return snprintf(buf, PAGE_SIZE, enabled ? "enabled\n" : "disabled\n");
+	return sysfs_emit(buf, enabled ? "enabled\n" : "disabled\n");
 }
 
 static ssize_t edid_show(struct file *filp, struct kobject *kobj,