mtd: MXC NAND support for 2KiB page size flashes

- Add support for 2KiB page size flashes
- Fix page address access for large pages
- Detect oob layout at runtime
- handle pagesize_2k variable
- Fix oob16 layout: reserve location 5 of oob area since it's used for bbt

Signed-off-by: Vladimir Barinov <vova.barinov@gmail.com>
Signed-off-by: Artem Bityutskiy <Artem.Bityutskiy@nokia.com>
Signed-off-by: David Woodhouse <David.Woodhouse@intel.com>