mtd: nand: subpage write support for hardware based ECC schemes

This patch adds support for subpage (partial-page) writes when using
hardware based ECC schemes.
Advantages:
(1) reduces storage overhead when using file-systems like UBIFS, which
store LEB header at page-size granularity.
(2) allows independent subpage writes, thereby increasing NAND storage
efficiency for non-page aligned data.
+ updated cafe_nand and lpc32xx_mlc NAND drivers for change in
chip->write_page interface.

Signed-off-by: Gupta, Pekon <pekon@ti.com>
Signed-off-by: Artem Bityutskiy <artem.bityutskiy@linux.intel.com>
Signed-off-by: David Woodhouse <David.Woodhouse@intel.com>