If you want to divide your device into parititions, then enable the configuration switch CONFIG_MTD_PARITIONS and define a paritioning scheme suitable to your board.

#define NUM_PARTITIONS 2
static struct mtd_partition partition_info[] = {
	{ .name = "Flash partition 1",
	  .offset =  0,
	  .size =    8 * 1024 * 1024 },
	{ .name = "Flash partition 2",
	  .offset =  MTDPART_OFS_NEXT,
	  .size =    MTDPART_SIZ_FULL },
};