tools: Remove unnecessary variables

There are several places where warnings variables are not needed,
remove them and directly return 0.

Signed-off-by: Lu Hongfei <luhongfei@vivo.com>
Link: https://lore.kernel.org/r/20230530075649.21661-1-luhongfei@vivo.com


Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org>