wpa_supplicant: Use PF_LOCAL instead of PF_INET*

Using a local socket circumvents the issue of needing any Internet
protocol (PF_INET or PF_INET6) support.
We only use interface ("i" group) ioctls on this socket so we can get
away with using PF_LOCAL instead of requring any Internet protocol
(PF_INET or PF_INET6) support on the system. This simplifies the
patch from 8c7149c73f8f.

PR: 286259
Noted by: kevans
Fixes: 8c7149c73f8f
MFC after: 2 weeks
Reviewed by: kevans, philip,

				zarychtam_plan-b.pwste.edu.pl (mzar)

Differential revision: https://reviews.freebsd.org/D50050