security/openvas: fix build on armv7 (again)

Some more printf type errors. These are really not important,
-Werror should be dropped as per policy so I don't have to revisit
this port yet again.

Approved by: portmgr (build fix blanket)
MFH: 2025Q3

(cherry picked from commit 4c8d901b75f85fb6a9cb8d2570274fef288d2e71)