mtd: atmel_nand: increase chip_delay

Some nand with 8k page size like Micron MT29F32G08ABAAAWP need more than 20us.
Signed-off-by: Raphaël Poggi <poggi.raph@gmail.com>
Signed-off-by: Brian Norris <computersforpeace@gmail.com>

drivers/mtd/nand/atmel_nand.c

@@ -2099,7 +2099,7 @@ static int atmel_nand_probe(struct platform_device *pdev)
 	}
 
 	nand_chip->ecc.mode = host->board.ecc_mode;
-	nand_chip->chip_delay = 20;		/* 20us command delay time */
+	nand_chip->chip_delay = 40;		/* 40us command delay time */
 
 	if (host->board.bus_width_16)	/* 16-bit bus width */
 		nand_chip->options |= NAND_BUSWIDTH_16;