wifi: rtw88: Remove duplicate NULL check before calling usb_kill/free_urb()

Both usb_kill_urb() and usb_free_urb() do the NULL check itself, so there
is no need to duplicate it prior to calling.

Fixes: a82dfd33 ("wifi: rtw88: Add common USB chip support")
Signed-off-by: Jinjie Ruan <ruanjinjie@huawei.com>
Acked-by: Sascha Hauer <s.hauer@pengutronix.de>
Acked-by: Ping-Ke Shih <pkshih@realtek.com>
Signed-off-by: Kalle Valo <kvalo@kernel.org>
Link: https://lore.kernel.org/r/20231008025852.1239450-1-ruanjinjie@huawei.com

drivers/net/wireless/realtek/rtw88/usb.c

@@ -611,7 +611,6 @@ static void rtw_usb_cancel_rx_bufs(struct rtw_usb *rtwusb)
 
 	for (i = 0; i < RTW_USB_RXCB_NUM; i++) {
 		rxcb = &rtwusb->rx_cb[i];
-		if (rxcb->rx_urb)
 		usb_kill_urb(rxcb->rx_urb);
 	}
 }
@@ -623,11 +622,9 @@ static void rtw_usb_free_rx_bufs(struct rtw_usb *rtwusb)
 
 	for (i = 0; i < RTW_USB_RXCB_NUM; i++) {
 		rxcb = &rtwusb->rx_cb[i];
-		if (rxcb->rx_urb) {
 		usb_kill_urb(rxcb->rx_urb);
 		usb_free_urb(rxcb->rx_urb);
 	}
-	}
 }
 
 static int rtw_usb_alloc_rx_bufs(struct rtw_usb *rtwusb)