ixgbe: Refactor transmit map and cleanup routines

This patch implements a partial refactor of the TX map/queue and cleanup
routines.  It merges the map and queue functionality and as a result
improves the transmit performance by avoiding unnecessary reads from memory.

Signed-off-by: Alexander Duyck <alexander.h.duyck@intel.com>
Tested-by: Phil Schmitt <phillip.j.schmitt@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>

drivers/net/ethernet/intel/ixgbe/ixgbe.h

@@ -96,6 +96,7 @@
 #define IXGBE_TX_FLAGS_IPV4		(u32)(1 << 3)
 #define IXGBE_TX_FLAGS_FCOE		(u32)(1 << 4)
 #define IXGBE_TX_FLAGS_FSO		(u32)(1 << 5)
+#define IXGBE_TX_FLAGS_MAPPED_AS_PAGE	(u32)(1 << 6)
 #define IXGBE_TX_FLAGS_VLAN_MASK	0xffff0000
 #define IXGBE_TX_FLAGS_VLAN_PRIO_MASK   0x0000e000
 #define IXGBE_TX_FLAGS_VLAN_SHIFT	16
@@ -141,14 +142,14 @@ struct vf_macvlans {
 /* wrapper around a pointer to a socket buffer,
  * so a DMA handle can be stored along with the buffer */
 struct ixgbe_tx_buffer {
-	struct sk_buff *skb;
-	dma_addr_t dma;
+	union ixgbe_adv_tx_desc *next_to_watch;
 	unsigned long time_stamp;
-	u16 length;
-	u16 next_to_watch;
-	unsigned int bytecount;
+	dma_addr_t dma;
+	u32 length;
+	u32 tx_flags;
+	struct sk_buff *skb;
+	u32 bytecount;
 	u16 gso_segs;
-	u8 mapped_as_page;
 };
 
 struct ixgbe_rx_buffer {