ixgbevf: Consolidate Tx context descriptor creation code

There is a good bit of redundancy between the Tx checksum and segmentation
offloads.  In order to reduce some of this I am moving the code for
creating a context descriptor into a separate function.
Signed-off-by: Alexander Duyck <alexander.h.duyck@intel.com>
Signed-off-by: Greg Rose <gregory.v.rose@intel.com>
Tested-by: Sibai Li <sibai.li@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>

drivers/net/ethernet/intel/ixgbevf/defines.h

@@ -251,6 +251,7 @@ struct ixgbe_adv_tx_context_desc {
 #define IXGBE_ADVTXD_TUCMD_L4T_TCP   0x00000800  /* L4 Packet TYPE of TCP */
 #define IXGBE_ADVTXD_TUCMD_L4T_SCTP  0x00001000  /* L4 Packet TYPE of SCTP */
 #define IXGBE_ADVTXD_IDX_SHIFT  4 /* Adv desc Index shift */
+#define IXGBE_ADVTXD_CC		0x00000080 /* Check Context */
 #define IXGBE_ADVTXD_POPTS_SHIFT      8  /* Adv desc POPTS shift */
 #define IXGBE_ADVTXD_POPTS_IXSM (IXGBE_TXD_POPTS_IXSM << \
 				 IXGBE_ADVTXD_POPTS_SHIFT)