DIGIC6: update cache maintenance routine
Created originally on Bitbucket by sombree
Was already merged in Bitbucket before import, marked as merged by the import user
DIGIC6: update cache maintenance routine
We want to just clean dcache without invalidating it. Also remove extra dsbs and isbs as they're already present in code in right places.
based on: https://community.arm.com/processors/b/blog/posts/caches-and-self-modifying-code http://infocenter.arm.com/help/index.jsp?topic=/com.arm.doc.ddi0363g/Bgbdbdjc.html