Admin Page : Update static function in get_modules() with use :: oper…

…ator. (#8178)

* fix minor changes

* Update class.jetpack-admin.php

@zinigor
I add all changes which is you suggest me. Please let me know if I miss some thing. Sir new changes  not tested so please test it when you get a chance.

Thanks

class.jetpack-admin.php

@@ -60,12 +60,12 @@ static function sort_requires_connection_last( $module1, $module2 ) {
 	// presentation like description, name, configuration url, etc.
 	function get_modules() {
 		include_once( JETPACK__PLUGIN_DIR . 'modules/module-info.php' );
-		$available_modules = $this->jetpack->get_available_modules();
-		$active_modules    = $this->jetpack->get_active_modules();
+		$available_modules = Jetpack::get_available_modules();
+		$active_modules    = Jetpack::get_active_modules();
 		$modules           = array();
 		$jetpack_active = Jetpack::is_active() || Jetpack::is_development_mode();
 		foreach ( $available_modules as $module ) {
-			if ( $module_array = $this->jetpack->get_module( $module ) ) {
+			if ( $module_array = Jetpack::get_module( $module ) ) {
 				/**
 				 * Filters each module's short description.
 				 *