scripts: coccinelle: boolinit: drop warnings on named constants

Coccinelle doesn't always have access to the values of named
(#define) constants, and they may likely often be bound to true
and false values anyway, resulting in false positives.  So stop
warning about them.

Signed-off-by: Julia Lawall <Julia.Lawall@lip6.fr>
Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>