MIPS: RB532: GPIO register offsets are relative to GPIOBASE

This patch fixes the wrong use of GPIO register offsets
in devices.c. To avoid further problems, use gpio_get_value
to return the NAND status instead of our own expanded code.

Also define the zero offset of the alternate function register to allow
consistent access.

Signed-off-by: Florian Fainelli <florian@openwrt.org>
Signed-off-by: Phil Sutter <n0-1@freewrt.org>
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
diff --git a/arch/mips/rb532/devices.c b/arch/mips/rb532/devices.c
index 2f22d71..c1c2918 100644
--- a/arch/mips/rb532/devices.c
+++ b/arch/mips/rb532/devices.c
@@ -118,7 +118,7 @@
 /* Resources and device for NAND */
 static int rb532_dev_ready(struct mtd_info *mtd)
 {
-	return readl(IDT434_REG_BASE + GPIOD) & GPIO_RDY;
+	return gpio_get_value(GPIO_RDY);
 }
 
 static void rb532_cmd_ctrl(struct mtd_info *mtd, int cmd, unsigned int ctrl)