Instead of passing error messages using a callback function (which becomes
awkward when used from a C++ class object) return distinct error codes from
chinachip_patch(). This also removes the kludge to support translations for
Rockbox Utility and moves the strings to translate to the installation class
where they belong.
As a side effect info messages won't be passed to Rockbox Utility anymore, but
the details of the patching progress aren't of that much interest for the user
git-svn-id: svn://svn.rockbox.org/rockbox/trunk@31115 a1c6a512-1295-4272-9138-f99709370657