MFC r343344
netmap: fix knote() argument to match the mutex state
The nm_os_selwakeup function needs to call knote() to wake up kqueue(9)
users. However, this function can be called from different code paths,
with different lock requirements.
This patch fixes the knote() call argument to match the relavant lock state.
Also, comments have been updated to reflect current code.
PR: https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=219846
Reported by: Aleksandr Fedorov <aleksandr.fedorov at itglobal.com>
Reviewed by: markj
Differential Revision: https://reviews.freebsd.org/D18876
UnifiedSplitRaw
