cfg80211: remove unused callback

The ieee80211 class registers a callback which actually does nothing.
Given that the callback is optional, and all its accesses are protected
by a NULL check, remove it entirely.

Signed-off-by: Matteo Croce <mcroce@microsoft.com>
Link: https://lore.kernel.org/r/20210208113356.4105-1-mcroce@linux.microsoft.com


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