[SPARK-26538][SQL] follow existing style

Author: a-shkarupin

sql/core/src/main/scala/org/apache/spark/sql/jdbc/PostgresDialect.scala

@@ -60,12 +60,10 @@ private object PostgresDialect extends JdbcDialect {
     case "bytea" => Some(BinaryType)
     case "timestamp" | "timestamptz" | "time" | "timetz" => Some(TimestampType)
     case "date" => Some(DateType)
-    case "numeric" | "decimal" => if (precision > 0) {
-      Some(DecimalType.bounded(precision, scale))
-    } else {
+    case "numeric" | "decimal" if precision > 0 => Some(DecimalType.bounded(precision, scale))
+    case "numeric" | "decimal" =>
       // SPARK-26538: handle numeric without explicit precision and scale.
       Some(DecimalType. SYSTEM_DEFAULT)
-    }
     case _ => None
   }