Remove duplicate coverage element in submission view

[tomniers]

If the user enabled the coverage element in the settings (Settings->Workflow->Submission->Metadata->Coverage), then there are two inputs for the coverage element in the submission view, one created by OJS and one created by the geoOJS Plugin. But both store their data in the same database element ("coverage"). Besides the initial coverage input field is not able to show the stored data, stored by the geoOJS plugin, correctly(like shown in the screenshot).
So the initial coverage input field must be disabled when using the geoOJS plugin.