spi: spi-mem: Add an ecc parameter to the spi_mem_op structure

Soon the SPI-NAND core will need a way to request a SPI controller to
enable ECC support for a given operation. This is because of the
pipelined integration of certain ECC engines, which are directly managed
by the SPI controller itself.

Introduce a spi_mem_op additional field for this purpose: ecc.

So far this field is left unset and checked to be false by all
the SPI controller drivers in their ->supports_op() hook, as they all
call spi_mem_default_supports_op().

Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com>
Acked-by: Pratyush Yadav <p.yadav@ti.com>
Reviewed-by: Boris Brezillon <boris.brezillon@collabora.com>
Reviewed-by: Tudor Ambarus <tudor.ambarus@microchip.com>
Link: https://lore.kernel.org/linux-mtd/20220127091808.1043392-7-miquel.raynal@bootlin.com