exit-air: remove redundant GetSubTreeType define

The type is already define in Utils.hpp

Change-Id: I80776a2968bb490e797fc262310de9686f9fa3e3
Signed-off-by: Alexander Hansen <alexander.hansen@9elements.com>
diff --git a/src/exit-air/ExitAirTempSensor.cpp b/src/exit-air/ExitAirTempSensor.cpp
index 09613b1..40650f6 100644
--- a/src/exit-air/ExitAirTempSensor.cpp
+++ b/src/exit-air/ExitAirTempSensor.cpp
@@ -111,10 +111,6 @@
 static void setMaxPWM(const std::shared_ptr<sdbusplus::asio::connection>& conn,
                       double value)
 {
-    using GetSubTreeType = std::vector<std::pair<
-        std::string,
-        std::vector<std::pair<std::string, std::vector<std::string>>>>>;
-
     conn->async_method_call(
         [conn,
          value](const boost::system::error_code ec, const GetSubTreeType& ret) {