flashimage: remove unnecessary ord()

[osresearch]

When running with an image file there is an error in the call to ord() on the body:

% python3 dumpflash.py -i raw.rom -P 0x2000 -O 64 --bp 64 -c check_ecc
PageSize: 0x2000
OOBSize: 0x40
PagePerBlock: 0x40
BlockSize: 0x80000
RawPageSize: 0x2040
FileSize: 0x10800000
PageCount: 0x8400

Traceback (most recent call last):
  File "dumpflash.py", line 160, in <module>
    flash_image_io.check_ecc()
  File "/home/hudson/sec/nand/dumpflash/dumpflash/flashimage.py", line 73, in check_ecc
    oob_ecc0 = ord(data[self.SrcImage.PageSize])
TypeError: ord() expected string of length 1, but int found

Fixing that one produces another error in the ecc; I can't verify if this change breaks the ftdi interface:

% python3 dumpflash.py -i raw.rom -P 0x2000 -O 64 --bp 64 -c check_ecc
PageSize: 0x2000
OOBSize: 0x40
PagePerBlock: 0x40
BlockSize: 0x80000
RawPageSize: 0x2040
FileSize: 0x10800000
PageCount: 0x8400

Traceback (most recent call last):
  File "dumpflash.py", line 160, in <module>
    flash_image_io.check_ecc()
  File "/home/hudson/sec/nand/dumpflash/dumpflash/flashimage.py", line 80, in check_ecc
    (ecc0, ecc1, ecc2) = ecc_calculator.calc(body)
  File "/home/hudson/sec/nand/dumpflash/dumpflash/ecc.py", line 52, in calc
    ch = ord(body[i])
TypeError: ord() expected string of length 1, but int found