dt-bindings: mtd: partition: Document the slc-mode property

Add a boolean property to force a specific partition attached to an MLC
NAND to be accessed in an emulated SLC mode this making this partition
immune to paired-pages corruptions.
Signed-off-by: Boris Brezillon <bbrezillon@kernel.org>
Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com>
Link: https://lore.kernel.org/linux-mtd/20200503155341.16712-6-miquel.raynal@bootlin.com

Documentation/devicetree/bindings/mtd/partition.txt

@@ -61,6 +61,9 @@ Optional properties:
   clobbered.
 - lock : Do not unlock the partition at initialization time (not supported on
   all devices)
+- slc-mode: This parameter, if present, allows one to emulate SLC mode on a
+  partition attached to an MLC NAND thus making this partition immune to
+  paired-pages corruptions
 
 Examples: