Don't use deprecated cmake variable

resources/ews/CMakeLists.txt

@@ -184,4 +184,4 @@ ecm_install_icons(
     )
 
 install(FILES ${CMAKE_CURRENT_SOURCE_DIR}/akonadi_ews_resource.notifyrc
-    DESTINATION "${KNOTIFYRC_INSTALL_DIR}")
+    DESTINATION "${KDE_INSTALL_KNOTIFY5RCDIR}")

resources/google-groupware/CMakeLists.txt

@@ -90,5 +90,5 @@ install(
 
 install(
   FILES akonadi_google_resource.notifyrc
-  DESTINATION ${KNOTIFYRC_INSTALL_DIR}
+  DESTINATION ${KDE_INSTALL_KNOTIFY5RCDIR}
 )