- Remove unnecessary memset for bbt
  All entries will be initialized at a few lines below
- Remove unnecessary initialization for mtd->erasesize
- Use write_whole_device()
Signed-off-by: NAkinobu Mita <akinobu.mita@gmail.com>
Signed-off-by: NArtem Bityutskiy <Artem.Bityutskiy@nokia.com>
Signed-off-by: NDavid Woodhouse <David.Woodhouse@intel.com>