wifi: iwlwifi: mvm: rs-fw: don't crash on missing channel

This is more of a workaround, with MLO we can get here with
the deflink not assigned. It's not critical right now that
we have this right, so WARN_ON_ONCE() and don't crash until
we can fix this area of the code.
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: Gregory Greenman <gregory.greenman@intel.com>
Link: https://lore.kernel.org/r/20230329100039.2b0d31bdb60b.I39d23c76eec16ac49f6ae3a6d5f7652041bde855@changeidSigned-off-by: Johannes Berg <johannes.berg@intel.com>

drivers/net/wireless/intel/iwlwifi/mvm/rs-fw.c

@@ -506,6 +506,9 @@ u16 rs_fw_get_max_amsdu_len(struct ieee80211_sta *sta)
 	const struct ieee80211_sta_vht_cap *vht_cap = &sta->deflink.vht_cap;
 	const struct ieee80211_sta_ht_cap *ht_cap = &sta->deflink.ht_cap;
 
+	if (WARN_ON_ONCE(!mvmsta->vif->bss_conf.chandef.chan))
+		return IEEE80211_MAX_MPDU_LEN_VHT_3895;
+
 	if (mvmsta->vif->bss_conf.chandef.chan->band == NL80211_BAND_6GHZ) {
 		switch (le16_get_bits(sta->deflink.he_6ghz_capa.capa,
 				      IEEE80211_HE_6GHZ_CAP_MAX_MPDU_LEN)) {