Fix handling DbType.Currency in FirebirdDialect and Oracle8iDialect (NH-3379)

Author: hazzik

src/NHibernate/Dialect/FirebirdDialect.cs

@@ -41,7 +41,6 @@ public FirebirdDialect()
 			RegisterColumnType(DbType.Boolean, "SMALLINT");
 			RegisterColumnType(DbType.Byte, "SMALLINT");
 			RegisterColumnType(DbType.Currency, "DECIMAL(18,4)");
-			RegisterColumnType(DbType.Currency, "DECIMAL($p,$s)");
 			RegisterColumnType(DbType.Date, "DATE");
 			RegisterColumnType(DbType.DateTime, "TIMESTAMP");
 			RegisterColumnType(DbType.Decimal, "DECIMAL(18,5)"); // NUMERIC(18,5) is equivalent to DECIMAL(18,5)

src/NHibernate/Dialect/Oracle8iDialect.cs

@@ -107,7 +107,6 @@ protected virtual void RegisterNumericTypeMappings()
 			RegisterColumnType(DbType.UInt64, "NUMBER(20,0)");
 
 			RegisterColumnType(DbType.Currency, "NUMBER(20,2)");
-			RegisterColumnType(DbType.Currency, "NUMBER($p,$s)");
 			RegisterColumnType(DbType.Single, "FLOAT(24)");
 			RegisterColumnType(DbType.Double, "DOUBLE PRECISION");
 			RegisterColumnType(DbType.Double, 19, "NUMBER($p,$s)");