tools: ynl: remove assigned but never used variable

tools: ynl: remove assigned but never used variable

These variables are assigned but never used according to Ruff. They can
then be safely removed.

This is linked to Ruff error F841 [1]:

  A variable that is defined but not used is likely a mistake, and
  should be removed to avoid confusion.

Link: https://docs.astral.sh/ruff/rules/unused-variable/
Signed-off-by: Matthieu Baerts (NGI0) <matttbe@kernel.org>
Reviewed-by: Donald Hunter <donald.hunter@gmail.com>
Reviewed-by: Asbjørn Sloth Tønnesen <ast@fiberby.net>
Link: https://patch.msgid.link/20250909-net-next-ynl-ruff-v1-3-238c2bccdd99@kernel.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>