Fail to netflix login after reboot

*I'm submitting a ...*
- [x ] bug report
- [ ] feature request
- [ ] support request

## General infomration

### Prerequisites

* [x] Are you running the latest version?
YES
### Description

After fresh install coreelec and netflix plugin i can nice and easy login to my netflix accout but
after reboot plugin asks me for login creditinals again, and after write them show that creditinals are wrong.

### Steps to Reproduce
1. Fresh install coreelec and plugin from zip file from gitbub.
2. Login.
3. Reboot device.
4. Run netflix plugin.
5. Write login and pass again
6. Creditinals Error.

**Expected behavior:**
Just once login and remeber my account.

**Actual behavior:**
Fail to run plugin after device rebooot
## Context (Environment)
Coreelec at s905 cpu box.
### Installation

* [x ] I installed the plugin via zip from the Releases page
* [ ] I´m using the Netflix Repo
* [ ] I´m using a different source (Please tell which)

### Operating System

* [ ] Linux (x86/x64)
* [ ] OSX (x86/x64)
* [ ] Windows (x86/x64)
* [x ] Linux (ARM)
* [ ] Android

#### Additional informatin on the environment

Coreelec 9.0.3

## Debug log

https://pastebin.com/sqsrP3wg

Start by reproducing the login flow on CoreELEC 9.0.3 with the Netflix plugin installed from the Releases zip, then inspect the linked debug log at pastebin.com/sqsrP3wg. Done means credentials remain valid after a device reboot and the plugin starts without requesting a failing login again.

Written by the indexing model from the issue text.