MX31: add accessor function to get a gpio

The patch adds an accessor function to get the value of a gpio.

Signed-off-by: Stefano Babic <sbabic@denx.de>
diff --git a/drivers/gpio/mx31_gpio.c b/drivers/gpio/mx31_gpio.c
index 737aafa..b07f038 100644
--- a/drivers/gpio/mx31_gpio.c
+++ b/drivers/gpio/mx31_gpio.c
@@ -71,3 +71,18 @@
 		l &= ~(1 << gpio);
 	__REG(gpio_ports[port] + GPIO_DR) = l;
 }
+
+int mx31_gpio_get(unsigned int gpio)
+{
+	unsigned int port = gpio >> 5;
+	u32 l;
+
+	if (port >= ARRAY_SIZE(gpio_ports))
+		return -1;
+
+	gpio &= 0x1f;
+
+	l = (__REG(gpio_ports[port] + GPIO_DR) >> gpio) & 0x01;
+
+	return l;
+}