• Remove empty key_update_* functions.
• Hide "struct ieee80211_node *" -> "struct run_node *" casting behind RUN_NODE() macro.
• Simplify IEEE80211_HAS_ADDR4 macro definition
• Fix a comment (desn't -> doesn't)

Submitted by: Andriy Voskoboinyk <s3erios at gmail com>
Differential Revision: https://reviews.freebsd.org/D3588