staging: r8188eu: use mgmt to set the category

Use the mgmt structure in issue_action_BA to set the category of the
outgoing frame. Remove the rtw_set_fixed_ie call.

We can now use the define directly, the category variable can be removed.

rtw_set_fixed_ie increments pattrib->pktlen, we have to do this ourselves
now (until we use a proper way to calculate the packet length).
Signed-off-by: Martin Kaiser <martin@kaiser.cx>
Link: https://lore.kernel.org/r/20220524090029.242584-7-martin@kaiser.cxSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/staging/r8188eu/core/rtw_mlme_ext.c

@@ -5365,7 +5365,6 @@ int issue_deauth_ex(struct adapter *padapter, u8 *da, unsigned short reason, int
 
 void issue_action_BA(struct adapter *padapter, unsigned char *raddr, unsigned char action, unsigned short status)
 {
-	u8 category = WLAN_CATEGORY_BACK;
 	u16 start_seq;
 	u16 BA_para_set;
 	u16 reason_code;
@@ -5408,7 +5407,8 @@ void issue_action_BA(struct adapter *padapter, unsigned char *raddr, unsigned ch
 	pframe += sizeof(struct ieee80211_hdr_3addr);
 	pattrib->pktlen = sizeof(struct ieee80211_hdr_3addr);
 
-	pframe = rtw_set_fixed_ie(pframe, 1, &(category), &pattrib->pktlen);
+	mgmt->u.action.category = WLAN_CATEGORY_BACK;
+	pattrib->pktlen++;
 	pframe = rtw_set_fixed_ie(pframe, 1, &(action), &pattrib->pktlen);
 
 	switch (action) {