mtd/nand:Fix wrong usage of is_blank() in fsl_ifc_run_command
Freescale IFC NAND Machine calculates ECC on 512byte sector and same is used in
fsl_ifc_run_command() during ECC status verification. Also this sector is passed
to is_blank() for blank checking. It is wrong at first place because
is_blank()'s implementation checks for Page size and OOB area size.
is_blank() should be called per page for main and OOB area verification.
Variables name are redefined to avoid confusion between buffer and ecc sector.