Fix navigation block link control zero value in it

[amustaque97]

Fixes: #36170

Description

In this commit, I have written condition properly. Zero was coming
because of conditional rendering where we should not put number on
the left side of && (logical and) operator.

How has this been tested?

1. Add a nav block
2. Start empty
3. Add a link
4. Select a URL to a page or post
5. Once done, click the link icon on the toolbar
6. Click the 'unlink' button in the link popover
7. Click on the 'Add link' text
8. Observe the link popover shows with a 0 in the top left corner

Screenshots

Types of changes

Checklist:

• My code is tested.
• My code follows the WordPress code style.
• My code follows the accessibility standards.
• I've tested my changes with keyboard and screen readers.
• My code has proper inline documentation.
• I've included developer documentation if appropriate.
• I've updated all React Native files affected by any refactorings/renamings in this PR (please manually search all *.native.js files for terms that need renaming or removal).

cc @Mamaduka

[ntsekouras]

Thanks @amustaque97 ! 💯