Bluetooth: btrtl: Fix a error code in rtl_load_config()

We accidentally return success if the kmemdup() fails.  It results in
a NULL dereference in the caller.

Fixes: 1110a2d ("Bluetooth: btrtl: Add RTL8822BE Bluetooth device")
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Johan Hedberg <johan.hedberg@intel.com>

drivers/bluetooth/btrtl.c

@@ -279,6 +279,8 @@ static int rtl_load_config(struct hci_dev *hdev, const char *name, u8 **buff)
 		return ret;
 	ret = fw->size;
 	*buff = kmemdup(fw->data, ret, GFP_KERNEL);
+	if (!*buff)
+		ret = -ENOMEM;
 
 	release_firmware(fw);