igb: Don't use NETDEV_FRAG_PAGE_MAX_SIZE in descriptor calculation

This change updates igb so that it will correctly perform the descriptor
count calculation.  Previously it was taking NETDEV_FRAG_PAGE_MAX_SIZE
into account with isn't really correct since a different value is used to
determine the size of the pages used for TCP.  That is actually determined
by SKB_FRAG_PAGE_ORDER.
Signed-off-by: Alexander Duyck <alexander.h.duyck@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/ethernet/intel/igb/igb_main.c

@@ -4974,6 +4974,7 @@ netdev_tx_t igb_xmit_frame_ring(struct sk_buff *skb,
 	struct igb_tx_buffer *first;
 	int tso;
 	u32 tx_flags = 0;
+	unsigned short f;
 	u16 count = TXD_USE_COUNT(skb_headlen(skb));
 	__be16 protocol = vlan_get_protocol(skb);
 	u8 hdr_len = 0;
@@ -4984,14 +4985,8 @@ netdev_tx_t igb_xmit_frame_ring(struct sk_buff *skb,
 	 *       + 1 desc for context descriptor,
 	 * otherwise try next time
 	 */
-	if (NETDEV_FRAG_PAGE_MAX_SIZE > IGB_MAX_DATA_PER_TXD) {
-		unsigned short f;
-
 	for (f = 0; f < skb_shinfo(skb)->nr_frags; f++)
 		count += TXD_USE_COUNT(skb_shinfo(skb)->frags[f].size);
-	} else {
-		count += skb_shinfo(skb)->nr_frags;
-	}
 
 	if (igb_maybe_stop_tx(tx_ring, count + 3)) {
 		/* this is a hard error */