hostap: Remove unused variable 'fc'

Fixes the following W=1 kernel build warning(s):

 In file included from drivers/net/wireless/intersil/hostap/hostap_cs.c:196:
 drivers/net/wireless/intersil/hostap/hostap_hw.c: In function ‘prism2_tx_80211’:
 drivers/net/wireless/intersil/hostap/hostap_hw.c:1806:18: warning: variable ‘fc’ set but not used [-Wunused-but-set-variable]
 1806 | u16 tx_control, fc;
 | ^~
 In file included from drivers/net/wireless/intersil/hostap/hostap_plx.c:264:
 drivers/net/wireless/intersil/hostap/hostap_hw.c: In function ‘prism2_tx_80211’:
 drivers/net/wireless/intersil/hostap/hostap_hw.c:1806:18: warning: variable ‘fc’ set but not used [-Wunused-but-set-variable]
 1806 | u16 tx_control, fc;
 | ^~
 In file included from drivers/net/wireless/intersil/hostap/hostap_pci.c:221:
 drivers/net/wireless/intersil/hostap/hostap_hw.c: In function ‘prism2_tx_80211’:
 drivers/net/wireless/intersil/hostap/hostap_hw.c:1806:18: warning: variable ‘fc’ set but not used [-Wunused-but-set-variable]
 1806 | u16 tx_control, fc;
 | ^~

Cc: Jouni Malinen <j@w1.fi>
Cc: Kalle Valo <kvalo@codeaurora.org>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Jakub Kicinski <kuba@kernel.org>
Cc: Cong Wang <xiyou.wangcong@gmail.com>
Cc: Taehee Yoo <ap420073@gmail.com>
Cc: linux-wireless@vger.kernel.org
Cc: netdev@vger.kernel.org
Signed-off-by: Lee Jones <lee.jones@linaro.org>
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>
Link: https://lore.kernel.org/r/20200826093401.1458456-20-lee.jones@linaro.org

drivers/net/wireless/intersil/hostap/hostap_hw.c

@@ -1803,7 +1803,7 @@ static int prism2_tx_80211(struct sk_buff *skb, struct net_device *dev)
 	struct hfa384x_tx_frame txdesc;
 	struct hostap_skb_tx_data *meta;
 	int hdr_len, data_len, idx, res, ret = -1;
-	u16 tx_control, fc;
+	u16 tx_control;
 
 	iface = netdev_priv(dev);
 	local = iface->local;
@@ -1826,7 +1826,6 @@ static int prism2_tx_80211(struct sk_buff *skb, struct net_device *dev)
 	/* skb->data starts with txdesc->frame_control */
 	hdr_len = 24;
 	skb_copy_from_linear_data(skb, &txdesc.frame_control, hdr_len);
- 	fc = le16_to_cpu(txdesc.frame_control);
 	if (ieee80211_is_data(txdesc.frame_control) &&
 	    ieee80211_has_a4(txdesc.frame_control) &&
 	    skb->len >= 30) {