mtd: nand: hynix: Add read-retry support for 1x nm MLC NANDs

All Hynix MLC NANDs produced with the 1x nm process support read-retry.
This read retry implementation should also be re-usable for other Hynix
NANDs, but the method to retrieve the read-retry parameters from the
read-retry OTP area might change a bit (some NANDs are even using a fixed
set of values instead of retrieving those information from the OTP area).

Signed-off-by: Boris Brezillon <boris.brezillon@free-electrons.com>
Acked-by: Richard Weinberger <richard@nod.at>