staging: wilc1000: tcp_process: fix a build warning

This patch fixes build warning "flags is used uninitialized" when
TCP_ACK_FILTER is defined.

Fixes: 562ed3f1 ("staging/wilc1000: pass struct wilc to most linux_wlan.c functions")
Signed-off-by: Glen Lee <glen.lee@atmel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/staging/wilc1000/wilc_wlan.c

@@ -234,6 +234,7 @@ static inline int tcp_process(struct net_device *dev, struct txq_entry_t *tqe)
 	vif = netdev_priv(dev);
 	wilc = vif->wilc;
 
+	spin_lock_irqsave(&wilc->txq_spinlock, flags);
 
 	eth_hdr_ptr = &buffer[0];
 	h_proto = ntohs(*((unsigned short *)&eth_hdr_ptr[12]));