rpm_specfile misspelled as rpm_spefile

### Description

> Please leave a brief description of the bug or feature request:

https://github.com/aboutcode-org/scancode-toolkit/blob/develop/src/packagedcode/rpm.py#L273

```
datasource_id = 'rpm_spefile'
```

should be:

```
datasource_id = 'rpm_specfile'
```

As I am not sure if this is now "intended behaviour" (it has been there for a number of years) I am not sending a PR.

@pombredanne