WIP: RS9116.NB0.NL.LNX.PURISM_FW_UPGRADE.1.0.5: updates for building against new kernels

(this of course breaks 5.3 kernels, so it's WIP)

• remove -Werror so that we build despite a switch case fallthrough
• update a mac80211 API just like we have done in Linux:

--- a/drivers/net/wireless/redpine/rsi_91x_mac80211.c
+++ b/drivers/net/wireless/redpine/rsi_91x_mac80211.c
@@ -2869,11 +2869,10 @@ void rsi_roc_timeout(struct timer_list *t)
        mutex_unlock(&common->mutex);
 }

-static int rsi_mac80211_cancel_roc(struct ieee80211_hw *hw)
+static int rsi_mac80211_cancel_roc(struct ieee80211_hw *hw, struct ieee80211_vif *vif)
 {
        struct rsi_hw *adapter = hw->priv;
        struct rsi_common *common = adapter->priv;
-       struct ieee80211_vif *vif = common->roc_vif;
        struct vif_priv *vif_info = (struct vif_priv *)vif->drv_priv;
        enum opmode intf_mode;