IB/ipoib: Delete unused struct

This structure is not needed since the introduction of commit
'c42687784b9a ("IB/ipoib: Scatter-Gather support in connected mode")'

Signed-off-by: Yuval Shaia <yuval.shaia@oracle.com>
Reviewed-by: Leon Romanovsky <leonro@mellanox.com>
Reviewed-by: Zhu Yanjun <yanjun.zhu@oracle.com>
Signed-off-by: Jason Gunthorpe <jgg@mellanox.com>

drivers/infiniband/ulp/ipoib/ipoib.h

@@ -193,11 +193,6 @@ struct ipoib_tx_buf {
 	u64		mapping[MAX_SKB_FRAGS + 1];
 };
 
-struct ipoib_cm_tx_buf {
-	struct sk_buff *skb;
-	u64		mapping;
-};
-
 struct ib_cm_id;
 
 struct ipoib_cm_data {