[FAB-7115]: Remove unused datatype

There is data type in coordinator.go module which is no longer in use
and could be safely removed, this commit cleans up and removes this
data type.

Change-Id: I7664376832e31f976f473a7850d670d343fb74b4
Signed-off-by: Artem Barger <bartem@il.ibm.com>

gossip/privdata/coordinator.go

@@ -237,8 +237,6 @@ func (c *coordinator) StoreBlock(block *common.Block, privateDataSets util.PvtDa
 	return nil
 }
 
-type dataSources map[rwSetKey][]*peer.Endorsement
-
 func (c *coordinator) fetchFromPeers(blockSeq uint64, ownedRWsets map[rwSetKey][]byte, privateInfo *privateDataInfo) {
 	dig2src := make(map[*gossip2.PvtDataDigest][]*peer.Endorsement)
 	privateInfo.missingKeys.foreach(func(k rwSetKey) {