[clang-tidy] Fix `readability-uppercase-literal-suffix` warning with hex literals (#156584)
This is a regression I introduced in #148275 and was [noticed
by](https://github.com/llvm/llvm-project/pull/148275#issuecomment-3246670841)
nettle. The check incorrectly fires on hex literals containing the
letter `b`.
(I felt a revert was unnecessary in this case. Maybe others disagree?)