HID: trivial devm conversion for special hid drivers

It is safe to use devres allocation within the hid subsystem:
- the devres release is called _after_ the call to .remove(), meaning
  that no freed pointers will exists while removing the device
- if a .probe() fails, devres releases all the allocated ressources
  before going to the next driver: there will not be ghost ressources
  attached to a hid device if several drivers are probed.

Given that, we can clean up a little some of the HID drivers. These ones
are trivial:
- there is only one kzalloc in the driver
- the .remove() callback contains only one kfree on top of hid_hw_stop()
- the error path in the probe is easy enough to be manually checked

Signed-off-by: Benjamin Tissoires <benjamin.tissoires@redhat.com>
Reviewed-by: Andy Shevchenko <andy.shevchenko@gmail.com>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>
diff --git a/drivers/hid/hid-zydacron.c b/drivers/hid/hid-zydacron.c
index e4cddec..1a660bd 100644
--- a/drivers/hid/hid-zydacron.c
+++ b/drivers/hid/hid-zydacron.c
@@ -169,7 +169,7 @@
 	int ret;
 	struct zc_device *zc;
 
-	zc = kzalloc(sizeof(*zc), GFP_KERNEL);
+	zc = devm_kzalloc(&hdev->dev, sizeof(*zc), GFP_KERNEL);
 	if (zc == NULL) {
 		hid_err(hdev, "can't alloc descriptor\n");
 		return -ENOMEM;
@@ -180,28 +180,16 @@
 	ret = hid_parse(hdev);
 	if (ret) {
 		hid_err(hdev, "parse failed\n");
-		goto err_free;
+		return ret;
 	}
 
 	ret = hid_hw_start(hdev, HID_CONNECT_DEFAULT);
 	if (ret) {
 		hid_err(hdev, "hw start failed\n");
-		goto err_free;
+		return ret;
 	}
 
 	return 0;
-err_free:
-	kfree(zc);
-
-	return ret;
-}
-
-static void zc_remove(struct hid_device *hdev)
-{
-	struct zc_device *zc = hid_get_drvdata(hdev);
-
-	hid_hw_stop(hdev);
-	kfree(zc);
 }
 
 static const struct hid_device_id zc_devices[] = {
@@ -217,7 +205,6 @@
 	.input_mapping = zc_input_mapping,
 	.raw_event = zc_raw_event,
 	.probe = zc_probe,
-	.remove = zc_remove,
 };
 module_hid_driver(zc_driver);