cfg80211: send events when devices are added/removed

We're currently sending NEW_WIPHY events for renames (which
is a bit odd, but now can't be changed), but also send them
for really new devices that register.

Also send DEL_WIPHY events when a device is removed, the
event ID for this was already reserved.

Signed-off-by: Johannes Berg <johannes.berg@intel.com>

diff --cc net/wireless/core.c
Simple merge

diff --cc net/wireless/nl80211.c
Simple merge

diff --cc net/wireless/nl80211.h
Simple merge