mtd: mxc_nand: preset_v1_v2: unlock all NAND flash blocks

For NFC v1, the unlock end block address was 0x4000, which would only
unlock the first 32 blocks of the NAND flash.  Change that value to
0xffff to unlock all available blocks, as is done for NFC v21 as well.

Signed-off-by: Michael Thalmeier <michael.thalmeier@hale.at>
Signed-off-by: Artem Bityutskiy <artem.bityutskiy@intel.com>