release: Include comms/usbmuxd to DVD to ensure ipheth(4) works

PR: 291370
Reviewed by: emaste, aokblast, dch
MFC after: 3 days
Sponsored by: The FreeBSD Foundation
Differential Revision: https://reviews.freebsd.org/D54074

(cherry picked from commit 90eda629964cbe4c2472aa3f1b8a427e60e78834)