iwlwifi(4) cross-references

From: Graham Perrin <grahamperrin_at_freebsd.org>
Date: Sat, 22 Jul 2023 04:27:29 UTC
iwlwifi(4) included references to iwm(4) and iwn(4) from the outset 
<https://github.com/freebsd/freebsd-src/commit/5a02ae5e8f2d74b7ac20fa2e0cd98c66d934905b#diff-d49468d6ece74430b6db22152a954e43930e2c22220361a5ee6a3e26e657d679R77-R78>. 


Neither iwm(4) 
<https://github.com/freebsd/freebsd-src/blob/bc310a95c58a3c570ed7e5103371453881e36ba1/share/man/man4/iwm.4#L171> 
nor iwn(4) 
<https://github.com/freebsd/freebsd-src/blob/bc310a95c58a3c570ed7e5103371453881e36ba1/share/man/man4/iwn.4#L189> 
refers to iwlwifi(4).