Remove unused param in Pool struct

contracts/staking/contracts/src/interfaces/IStructs.sol

@@ -94,11 +94,9 @@ interface IStructs {
     }
 
     /// @dev Holds the metadata for a staking pool.
-    /// @param initialized True iff the balance struct is initialized.
     /// @param operator of the pool.
     /// @param operatorShare Fraction of the total balance owned by the operator, in ppm.
     struct Pool {
-        bool initialized;
         address payable operator;
         uint32 operatorShare;
     }

contracts/staking/contracts/src/staking_pools/MixinStakingPool.sol

@@ -65,7 +65,6 @@ contract MixinStakingPool is
 
         // create and store pool
         IStructs.Pool memory pool = IStructs.Pool({
-            initialized: true,
             operator: operator,
             operatorShare: operatorShare
         });