I've applied your code above to my test site, and it gives the following footer:
(Social Icons) · © 2014 Customizr Test · Powered by Softcomimagio Ltd · Back to top
However, you do have an unwanted [CR] in the middle so copy & paste exactly:
add_filter('tc_credits_display', 'my_custom_credits');
function my_custom_credits(){
$credits = 'Powered by Softcomimagio Ltd';
$newline_credits = '';
return '
<div class="span4 credits">
<p> · © '.esc_attr( date( 'Y' ) ).' <a href="'.esc_url( home_url() ).'" title="'.esc_attr(get_bloginfo()).'" rel="bookmark">'.esc_attr(get_bloginfo()).'</a> · '.($credits ? $credits : 'Designed by <a href="http://www.themesandco.com/">Themes & Co</a>').' ·'.($newline_credits ? '<br />· '.$newline_credits.' ·' : '').'</p> </div>';
}