The redboot partitioning code currently searches for a FIS table entry
named "RedBoot" (including the trailing \0) in one of the first three
entries to try and verify that the sector it is looking at really is a
FIS partition table.

Firstly it fails when RedBoot is stored in some other Flash chip such as
a boot PROM, in this case there is no "RedBoot" entry in the partition
table. However there will always be a "FIS directory" entry in any valid
FIS directory.
        
Secondly it can fail since the RedBoot entry is not always in the first
3 slots -- this can happen for example on an x86 based platform where
the processor expects the boot device to be at the top of memory rather
than the bottom and so RedBoot is at the end of the flash device.
Equally when using "FIS directory" as the entry to search for it very
likely is not in the first three since the directory is typically at the
end of the flash.
Signed-off-by: Ian Campbell <icampbell@arcom.com>
Signed-off-by: David Woodhouse <dwmw2@infradead.org>