bmc: drop unused Session::State

Originally added and used to track the state of the Session object,
however, we have other mechanisms to know this information and therefore
never check this.  Remove unused Session::State

Signed-off-by: Patrick Venture <venture@google.com>
Change-Id: Ib4a14cea94f919c3b88e9f944e7cb9498613b3b2
diff --git a/firmware_handler.hpp b/firmware_handler.hpp
index 9aab59a..6aae5b6 100644
--- a/firmware_handler.hpp
+++ b/firmware_handler.hpp
@@ -29,8 +29,7 @@
      * @param[in] the active path to which this corresponds.
      */
     explicit Session(const std::string& path) :
-        dataHandler(nullptr), imageHandler(nullptr), flags(0),
-        state(State::closed), activePath(path)
+        dataHandler(nullptr), imageHandler(nullptr), flags(0), activePath(path)
     {
     }
 
@@ -48,16 +47,6 @@
     /** The flags used to open the session. */
     std::uint16_t flags;
 
-    /** A sesion can be for an image (or tarball) or the hash. */
-    enum class State
-    {
-        open = 0,
-        closed = 1,
-    };
-
-    /** The current state of this session. */
-    State state;
-
     /** The active path. */
     std::string activePath;
 };