staging: vt6655: remove unnecessary variable skb_dma

skb_dma flips from 0 to the contents buf_dma.

This is nolonger necessary so use buf_dma directly
and remove skb_dma altogether.
Signed-off-by: Malcolm Priestley <tvboxspy@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/staging/vt6655/desc.h

@@ -256,7 +256,6 @@ typedef struct tagDEVICE_TD_INFO {
 	void *mic_hdr;
 	struct sk_buff *skb;
 	unsigned char *buf;
-	dma_addr_t          skb_dma;
 	dma_addr_t          buf_dma;
 	dma_addr_t          curr_desc;
 	unsigned long dwReqCount;

drivers/staging/vt6655/device_main.c

@@ -970,7 +970,6 @@ static void device_free_tx_buf(struct vnt_private *pDevice, PSTxDesc pDesc)
 	if (skb)
 		ieee80211_tx_status_irqsafe(pDevice->hw, skb);
 
-	pTDInfo->skb_dma = 0;
 	pTDInfo->skb = NULL;
 	pTDInfo->byFlags = 0;
 }
@@ -1201,7 +1200,7 @@ static int vnt_tx_packet(struct vnt_private *priv, struct sk_buff *skb)
 	head_td->m_td1TD1.wReqCount =
 			cpu_to_le16((u16)head_td->pTDInfo->dwReqCount);
 
-	head_td->buff_addr = cpu_to_le32(head_td->pTDInfo->skb_dma);
+	head_td->buff_addr = cpu_to_le32(head_td->pTDInfo->buf_dma);
 
 	/* Poll Transmit the adapter */
 	wmb();

drivers/staging/vt6655/rxtx.c

@@ -1202,7 +1202,6 @@ s_cbFillTxBufHead(struct vnt_private *pDevice, unsigned char byPktType,
 
 	ptdCurr->pTDInfo->dwReqCount = cbReqCount;
 	ptdCurr->pTDInfo->dwHeaderLength = cbHeaderLength;
-	ptdCurr->pTDInfo->skb_dma = ptdCurr->pTDInfo->buf_dma;
 
 	return cbHeaderLength;
 }