In preparation for use with sansapatcher, change portalplayer bootloaders to read firmwares in mi4 format.

When loading the OF:
1) first try to load from a hidden disk partition
2) try loading /System/OF.mi4
3) finally fall back to loading /System/OF.bin which is what the old bootloader used.


git-svn-id: svn://svn.rockbox.org/rockbox/trunk@12802 a1c6a512-1295-4272-9138-f99709370657

bootloader/common.c

@@ -97,6 +97,8 @@ char *strerror(int error)
         return "Bad checksum";
     case EFILE_TOO_BIG:
         return "File too big";
+    case EINVALID_FORMAT:
+        return "Invalid file format";
     default:
         return "Unknown";
     }