Fix deprecated warning with function name update

Fix notice during debug: 
Deprecated local plugin navigation callback: Please rename 'ltiprovider_extends_navigation' to 'local_ltiprovider_extends_navigation'. Support for the old callback will be dropped after the release of 2.4
line 1236 of /lib/navigationlib.php: call to debugging()
line 2920 of /lib/navigationlib.php: call to global_navigation->initialise()
line 766 of /lib/pagelib.php: call to navbar->has_items()
line 4 of /theme/base/layout/general.php: call to moodle_page->has_navbar()
line 804 of /lib/outputrenderers.php: call to include()
line 734 of /lib/outputrenderers.php: call to core_renderer->render_page_layout()
line 230 of /course/view.php: call to core_renderer->header()