fix memory leak of dirty image

fix memory leak of dirty image
if file was chaned by somebody, it was added to dirty list during cache request.
currently this dirty image added to cache->dirty list and never freed until image shutdown.
but dirty image of chaned file never used so add delete code for memory efficiency.
and fix bad indentation.

git-svn-id: svn+ssh://svn.enlightenment.org/var/svn/e/trunk/evas@67604 7cbeb6ba-43b4-40fd-8cce-4c39aea84d33