cap_net: correct capability name from addr2name to name2addr

Previously, while checking name2addr capabilities, we mistakenly used
the addr2name set. This error could cause a process to inadvertently
reset its limitations.

Reported by: Shawn Webb <shawn.webb@hardenedbsd.org>

(cherry picked from commit afd74c400075d94e01dd3430844bb290834660ef)