Extend return codes for chinachip_patch().

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
anyway.

git-svn-id: svn://svn.rockbox.org/rockbox/trunk@31115 a1c6a512-1295-4272-9138-f99709370657

rbutil/rbutilqt/base/bootloaderinstallchinachip.h

@@ -33,7 +33,6 @@ class BootloaderInstallChinaChip : public BootloaderInstallBase
         BootloaderInstallBase::BootloaderType installed(void);
         Capabilities capabilities(void);
         QString ofHint();
-        void logString(char* buffer, va_list args, int type);
 
     private slots:
         void installStage2(void);