Always define and use ENABLE_LOGGING

Always define and use ENABLE_LOGGING

Convert the "if defined FOO" pre-processor checks for compiler ones "if
(FOO == 1)".

This makes things easier to reason with and ensures both code-paths are
build-tested. In case, the option is disabled DCE will kick in (assuming
you're not force disabling all optimisations) and remove the respective
code.

Signed-off-by: Emil Velikov <emil.l.velikov@gmail.com>
Link: https://github.com/kmod-project/kmod/pull/173
Signed-off-by: Lucas De Marchi <lucas.de.marchi@gmail.com>