clang: remove True option to getVar calls

[petermarko]

Layer cleanup similar to https://git.openembedded.org/openembedded-core/commit/?id=26c74fd10614582e177437608908eb43688ab510

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• [x] Changes have been tested
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[petermarko]

Can this be picked to scarthgap or do I need to create another PR?

[kraj]

Can this be picked to scarthgap or do I need to create another PR?

Please create a separate PR for every branch it needs to go in