lnwallet: update to 20 byte revocation hashes

lnwallet/reservation.go

@@ -36,7 +36,7 @@ type ChannelContribution struct {
 
 	// Hash to be used as the revocation for the initial version of this
 	// party's commitment transaction.
-	RevocationHash [wire.HashSize]byte
+	RevocationHash [20]byte
 
 	// The delay (in blocks) to be used for the pay-to-self output in this
 	// party's version of the commitment transaction.