HID: wacom: convert sysfs sprintf/snprintf family to sysfs_emit

Fix the following coccicheck warning:

./drivers/hid/wacom_sys.c:1828:8-16: WARNING: use scnprintf or sprintf.

Reported-by: Abaci Robot<[e-mail]>
Signed-off-by: Jiapeng Chong <[e-mail]>
Signed-off-by: Jiri Kosina <[e-mail]>

drivers/hid/wacom_sys.c

···
 	struct hid_device *hdev = to_hid_device(dev);
 	struct wacom *wacom = hid_get_drvdata(hdev);
 
-	return snprintf(buf, PAGE_SIZE, "%i\n", wacom->wacom_wac.bt_high_speed);
+	return sysfs_emit(buf, "%i\n", wacom->wacom_wac.bt_high_speed);
 }
 
 static ssize_t wacom_store_speed(struct device *dev,