[MTD] [NAND] at91_nand rdy_pin fix

The patch below fixes nand driver for AT91 boards which do not have NAND
R/B signal connected to gpio (rdy_pin is not connected).
Signed-off-by: Ivan Kuten <ivan.kuten@promwad.com>
Acked-by: Andrew Victor <andrew@sanpeople.com>
Signed-off-by: David Woodhouse <dwmw2@infradead.org>

drivers/mtd/nand/at91_nand.c

@@ -128,7 +128,10 @@ static int __init at91_nand_probe(struct platform_device *pdev)
 	nand_chip->IO_ADDR_R = host->io_base;
 	nand_chip->IO_ADDR_W = host->io_base;
 	nand_chip->cmd_ctrl = at91_nand_cmd_ctrl;
+
+	if (host->board->rdy_pin)
 		nand_chip->dev_ready = at91_nand_device_ready;
+
 	nand_chip->ecc.mode = NAND_ECC_SOFT;	/* enable ECC */
 	nand_chip->chip_delay = 20;		/* 20us command delay time */