Fixed bug in alt text of score dots

[Reported by Rocket Pixels](http://wordpress.org/support/topic/dots-on-hover-over-show-na-tooltip)

![In SEO columns](http://snag.gy/1yryh.jpg) ![In Publish box](http://snag.gy/RU4Nb.jpg)
For the scoring dots, both the css class as well as the title/alt text needs to be retrieved.
As it was, the $score variable was being re-used for the css class and then the title was being retrieved with the css class as the $val resulting in all titles/alt texts showing 'na'.

Fixed now.