mtd: spinand: Fix kernel doc

The @DaTa buffer is 5 bytes, not 4, it has been extended for the need of
devices with an extra ID bytes.

Fixes: 34a9567 ("mtd: spinand: Add support for 5-byte IDs")
Reviewed-by: Tudor Ambarus <tudor.ambarus@linaro.org>
Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com>

Author: miquelraynal

include/linux/mtd/spinand.h

@@ -287,7 +287,7 @@ struct spinand_device;
 
 /**
  * struct spinand_id - SPI NAND id structure
- * @data: buffer containing the id bytes. Currently 4 bytes large, but can
+ * @data: buffer containing the id bytes. Currently 5 bytes large, but can
  *	  be extended if required
  * @len: ID length
  */