[buff] The little push that Garen needs

In the patch update you mentioned that Garen needs a little extra help to be a competitive top lane. I think an easy update that shouldn't break too much is to his w.

Courage: add -> when activated, Perseverance is activated. add -> While active Perseverance will not go onto cooldown, when damage is taken.

I think this fits his character concept, and adds a little(?) extra buff to Garen. Adding sustain instead of more damage.