[MTD] OneNAND: Reduce Double Density Package (DDP) operations

- DDP code clean-up
- Reduce block & bufferram operations in DDP

Signed-off-by: Kyungmin Park <kyungmin.park@samsung.com>

diff --cc drivers/mtd/onenand/onenand_base.c
Simple merge

diff --cc include/linux/mtd/onenand.h
Simple merge

diff --cc include/linux/mtd/onenand_regs.h
Simple merge