saltclass tops doesn't resolve __salt__ object functions

[paulbsd]

What does this PR do?

Actually saltclass tops module doesn't resolve __salt__ object functions declared in saltclass pillar.
This fix resolves issue in latest stable version 3005.1.

What issues does this PR fix or reference?

Fixes: #50501

Previous Behavior

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New Behavior

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Merge requirements satisfied?

[NOTICE] Bug fixes or features added to Salt require tests.

• Docs
• Changelog - https://docs.saltproject.io/en/master/topics/development/changelog.html
• Tests written/updated

Commits signed with GPG?

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