ifconfig: 80211, add line break after key info

Beauty correction for verbose mode or in case we print multiple key
information to not continue with the next options directly after
as we did so far, e.g.:
AES-CCM 2:128-bit
AES-CCM 3:128-bit powersavemode ...

Sponsored by: The FreeBSD Foundation
Reviewed by: adrian
Differential Revision: https://reviews.freebsd.org/D29393

(cherry picked from commit 5ba4c8de15210bbc026c41b77b23d5af06613fe6)