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.h

@@ -27,6 +27,7 @@
 #define     EREAD_IMAGE_FAILED      -4
 #define     EBAD_CHKSUM             -5
 #define     EFILE_TOO_BIG           -6
+#define     EINVALID_FORMAT         -7
 
 /* Set this to true to enable lcd_update() in the printf function */
 extern bool verbose;