fix(eslint-plugin): [naming-convention] fix filter option

[bradzacher]

Fixes #1478

I had the logic just slightly wrong

[typescript-eslint]

Thanks for the PR, @bradzacher!

typescript-eslint is a 100% community driven project, and we are incredibly grateful that you are contributing to that community.

The core maintainers work on this in their personal time, so please understand that it may not be possible for them to review your work immediately.

Thanks again!

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[codecov]

Codecov Report

Merging #1482 into master will increase coverage by 0.01%.
The diff coverage is 100%.

@@            Coverage Diff             @@
##           master    #1482      +/-   ##
==========================================
+ Coverage   95.55%   95.56%   +0.01%     
==========================================
  Files         144      146       +2     
  Lines        6569     6591      +22     
  Branches     1878     1881       +3     
==========================================
+ Hits         6277     6299      +22     
  Misses        111      111              
  Partials      181      181

Impacted Files	Coverage Δ
...kages/eslint-plugin/src/rules/naming-convention.ts	88.45% <100%> (ø)	⬆️
packages/eslint-plugin/src/rules/index.ts	100% <0%> (ø)	⬆️
packages/eslint-plugin/src/rules/ban-ts-ignore.ts	100% <0%> (ø)	⬆️
packages/eslint-plugin/src/rules/ban-ts-comment.ts	100% <0%> (ø)
...n/src/rules/no-non-null-asserted-optional-chain.ts	100% <0%> (ø)