Fix XSS in view_filters_page.php

The value of the view_type parameter was not sanitized before being
displayed as a hidden input.

This vulnerability was reported by Etienne Landais.

Fixes #22497

view_filters_page.php

@@ -105,7 +105,7 @@
 
 	<?php # CSRF protection not required here - form does not result in modifications ?>
 	<input type="hidden" name="type" value="1" />
-	<input type="hidden" name="view_type" value="<?php echo $f_view_type; ?>" />
+	<input type="hidden" name="view_type" value="<?php echo $t_filter['_view_type']; ?>" />
 	<?php
 		if( $f_for_screen == false ) {
 			print '<input type="hidden" name="print" value="1" />';