Remove unused member variable.

eeschema/sch_io/altium/sch_io_altium.cpp

@@ -3659,8 +3659,7 @@ void SCH_IO_ALTIUM::ParsePowerPort( const std::map<wxString, wxString>& aPropert
     {
         libSymbol = powerSymbolIt->second; // cache hit
     }
-    else if( LIB_SYMBOL* alreadyLoaded = m_pi->LoadSymbol( getLibFileName().GetFullPath(), symName,
-                                                           m_properties.get() ) )
+    else if( LIB_SYMBOL* alreadyLoaded = m_pi->LoadSymbol( getLibFileName().GetFullPath(), symName ) )
     {
         libSymbol = alreadyLoaded;
     }

eeschema/sch_io/altium/sch_io_altium.h

@@ -229,7 +229,6 @@ private:
     bool           m_isIntLib;          // Flag to indicate Integrated Library
 
     IO_RELEASER<SCH_IO>                m_pi;                  // Plugin to create KiCad symbol library.
-    std::unique_ptr<std::map<std::string, UTF8>>  m_properties;    // Library plugin properties.
 
     std::unique_ptr<TITLE_BLOCK>       m_currentTitleBlock;   // Will be assigned at the end of parsing
                                                               //   a sheet