NAND subsystem is being slightly reworked to store ECC details in
separated fields. In future we'll want to add support for more DT
properties as specifying every possible setup with a single
"nand-ecc-mode" is a pretty bad idea.
To allow this let's add a helper that will support something like
"nand-ecc-algo" in future. Right now we use it for keeping backward
compatibility.
Signed-off-by: Rafał Miłecki <zajec5@gmail.com>
Signed-off-by: Boris Brezillon <boris.brezillon@free-electrons.com>