staging: wilc1000: remove unused varialbe tx_buffer_offset

This patch removes unused variable tx_buffer_offset of wilc_wlan_dev_t.
Signed-off-by: Glen Lee <glen.lee@atmel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/staging/wilc1000/wilc_wlan.c

@@ -13,7 +13,6 @@ typedef struct {
 	u8 *rx_buffer;
 	u32 rx_buffer_offset;
 	u8 *tx_buffer;
-	u32 tx_buffer_offset;
 
 	unsigned long txq_spinlock_flags;