Printing a function on a content type page?
The error message itself is clear I think. You are trying to print an object as a string. 
otherwise, your query seems correct. 

function innovista_get_page_children() {

 $result = db_query("SELECT link_path FROM {menu_links}");
 return $result;

}


&lt;?php
$results = innovista_get_page_children();
print '&lt;pre&gt;';
foreach($results as $result){
    print_r($result);
}
print '&lt;/pre&gt;';
?&gt;


Now you will see a formatted variable information of each $result. 
it will look like

stdClass Object (
  [link_path] =&gt; admin/structure/views 
)


So when you print the results, it will be like,

&lt;?php
    $results = innovista_get_page_children();
    foreach($results as $result){
      print $result-&gt;link_path;
      print '&lt;br/&gt;';
    }
?&gt;


However, keep in mind that it's never OK to print link paths or database queries like this. It will cause huge performance problems and will arise security problems. 
Try to use url() and/or l() functions for links (suggested it because you seem to make a link). 
Also, in most cases, there is a function for core/contrib modules to retrive data.