mtd: nand: Let ECC engines advertize the exact number of steps

This is an information that might be useful for specific uses, so
export it, which might avoid having to guess the number of steps when
necessary.
Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com>
Tested-by: Adam Ford <aford173@gmail.com> #logicpd Torpedo
Link: https://lore.kernel.org/linux-mtd/20210127203020.9574-2-miquel.raynal@bootlin.com

include/linux/mtd/nand.h

@@ -231,12 +231,14 @@ struct nand_ops {
 /**
  * struct nand_ecc_context - Context for the ECC engine
  * @conf: basic ECC engine parameters
+ * @nsteps: number of ECC steps
  * @total: total number of bytes used for storing ECC codes, this is used by
  *         generic OOB layouts
  * @priv: ECC engine driver private data
  */
 struct nand_ecc_context {
 	struct nand_ecc_props conf;
+	unsigned int nsteps;
 	unsigned int total;
 	void *priv;
 };