wifi: mac80211: remove ieee80211_set_hw_80211_encap()

While fixing kernel-doc issues it was discovered that the
ieee80211_set_hw_80211_encap() prototype doesn't actually have an
implementation, so remove it.

Note the implementation was removed in commit 6aea26ce ("mac80211:
rework tx encapsulation offload API").
Signed-off-by: Jeff Johnson <quic_jjohnson@quicinc.com>
Reviewed-by: Randy Dunlap <rdunlap@infradead.org>
Link: https://msgid.link/20240329-mac80211-kdoc-retval-v1-1-5e4d1ad6c250@quicinc.comSigned-off-by: Johannes Berg <johannes.berg@intel.com>

include/net/mac80211.h

@@ -7483,18 +7483,6 @@ u32 ieee80211_calc_rx_airtime(struct ieee80211_hw *hw,
 u32 ieee80211_calc_tx_airtime(struct ieee80211_hw *hw,
 			      struct ieee80211_tx_info *info,
 			      int len);
-/**
- * ieee80211_set_hw_80211_encap - enable hardware encapsulation offloading.
- *
- * This function is used to notify mac80211 that a vif can be passed raw 802.3
- * frames. The driver needs to then handle the 802.11 encapsulation inside the
- * hardware or firmware.
- *
- * @vif: &struct ieee80211_vif pointer from the add_interface callback.
- * @enable: indicate if the feature should be turned on or off
- */
-bool ieee80211_set_hw_80211_encap(struct ieee80211_vif *vif, bool enable);
-
 /**
  * ieee80211_get_fils_discovery_tmpl - Get FILS discovery template.
  * @hw: pointer obtained from ieee80211_alloc_hw().