ubi-utils: bin2nand, nand2bin add support of different ecc layouts

ubi-utils: bin2nand, nand2bin add support of different ecc layouts

Both tools were lacking support of alternate ECC layouts. Only our intitial
format was supported. With this change, it should be very easy to add more
layouts in addtion to the already supported ones, which are: IBM (our format),
and the MTD default layout. NAND OOB sizes of 512 and 2048 are currently
supported.

In contrast to the old version of bin2nand, the holes inbetween the ECC data
is now not filled with 0x00 anymore but instead 0xff (like deleted flash) is
used. This should not cause any difference. The testcase reflects the different
layouts too.

Signed-off-by: Frank Haverkamp <haver@vnet.ibm.com>