pw: Add a missing chown() when creating dirs in mkdir_home_parents()

mkdir_home_parents() effectively performs a mkdir -p of the root home
directory. It chowns the home directory to 0, 0, but doesn't do so for
the intermediate directories. Add an explicit chown() call for those
too. Fix a long line while here.

Reviewed by: bapt
MFC after: 1 week
Sponsored by: The FreeBSD Foundation
Sponsored by: Klara, Inc.
Differential Revision: https://reviews.freebsd.org/D52587

(cherry picked from commit 41b2a80353e0dd04939cc260d5763854a264c158)