mac80211: make ieee80211_wep_init() return void

This function always returns 0, so there's no point in returning int.
Make it void and remove the impossible error-path when calling it.

Signed-off-by: Luca Coelho <luciano.coelho@intel.com>
Link: https://lore.kernel.org/r/20200131111300.891737-11-luca@coelho.fi


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