"Columns" is misspelled ($colums_count) in theme_field_ui_table()

In theme_field_ui_table(), the variable $colums_count is a misspelling. Rename it to $columns_count.

[milankovitch:drupal | Fri 13:48:09] $ grep -r "colums" *
core/modules/field_ui/field_ui.admin.inc:  $colums_count = 0;
core/modules/field_ui/field_ui.admin.inc:    $colums_count += (is_array($header) && isset($header['colspan']) ? $header['colspan'] : 1);
core/modules/field_ui/field_ui.admin.inc:          array('data' => $region['title'], 'colspan' => $colums_count),
core/modules/field_ui/field_ui.admin.inc:          array('data' => $region['message'], 'colspan' => $colums_count),