remove unused (#2676)

Co-authored-by: Bastian Köcher <info@kchr.de>

runtime/kusama/src/lib.rs

@@ -612,10 +612,6 @@ impl pallet_offences::Config for Runtime {
 
 impl pallet_authority_discovery::Config for Runtime {}
 
-parameter_types! {
-	pub const SessionDuration: BlockNumber = EPOCH_DURATION_IN_BLOCKS as _;
-}
-
 parameter_types! {
 	pub NposSolutionPriority: TransactionPriority =
 		Perbill::from_percent(90) * TransactionPriority::max_value();

runtime/polkadot/src/lib.rs

@@ -658,10 +658,6 @@ impl pallet_offences::Config for Runtime {
 
 impl pallet_authority_discovery::Config for Runtime {}
 
-parameter_types! {
-	pub const SessionDuration: BlockNumber = EPOCH_DURATION_IN_BLOCKS as _;
-}
-
 parameter_types! {
 	pub NposSolutionPriority: TransactionPriority =
 		Perbill::from_percent(90) * TransactionPriority::max_value();

runtime/westend/src/lib.rs

@@ -409,10 +409,6 @@ impl pallet_offences::Config for Runtime {
 
 impl pallet_authority_discovery::Config for Runtime {}
 
-parameter_types! {
-	pub const SessionDuration: BlockNumber = EPOCH_DURATION_IN_BLOCKS as _;
-}
-
 parameter_types! {
 	pub const NposSolutionPriority: TransactionPriority = TransactionPriority::max_value() / 2;
 	pub const ImOnlineUnsignedPriority: TransactionPriority = TransactionPriority::max_value();