wifi: iwlwifi: mvm: always set MH len in offload_assist

Some versions of the new hardware don't have a functional
version of the new offload method, but still have stricter
checks on the MAC header (MH) length in the offload assist
word. Include that even if checksumming isn't offloaded to
hardware.
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: Gregory Greenman <gregory.greenman@intel.com>
Link: https://lore.kernel.org/r/20230612184434.bba713f7495a.Idbc8e3ce313b51af4060326e0191bd338b3163a2@changeidSigned-off-by: Johannes Berg <johannes.berg@intel.com>

drivers/net/wireless/intel/iwlwifi/mvm/tx.c

@@ -44,9 +44,9 @@ static u16 iwl_mvm_tx_csum_pre_bz(struct iwl_mvm *mvm, struct sk_buff *skb,
 				  struct ieee80211_tx_info *info, bool amsdu)
 {
 	struct ieee80211_hdr *hdr = (void *)skb->data;
+	u16 mh_len = ieee80211_hdrlen(hdr->frame_control);
 	u16 offload_assist = 0;
 #if IS_ENABLED(CONFIG_INET)
-	u16 mh_len = ieee80211_hdrlen(hdr->frame_control);
 	u8 protocol = 0;
 
 	/* Do not compute checksum if already computed */
@@ -118,6 +118,8 @@ static u16 iwl_mvm_tx_csum_pre_bz(struct iwl_mvm *mvm, struct sk_buff *skb,
 	else
 		udp_hdr(skb)->check = 0;
 
+out:
+#endif
 	/*
 	 * mac header len should include IV, size is in words unless
 	 * the IV is added by the firmware like in WEP.
@@ -130,8 +132,6 @@ static u16 iwl_mvm_tx_csum_pre_bz(struct iwl_mvm *mvm, struct sk_buff *skb,
 	mh_len /= 2;
 	offload_assist |= mh_len << TX_CMD_OFFLD_MH_SIZE;
 
-out:
-#endif
 	if (amsdu)
 		offload_assist |= BIT(TX_CMD_OFFLD_AMSDU);
 	else if (ieee80211_hdrlen(hdr->frame_control) % 4)