blackfin: gpio: fix compile error if !CONFIG_GPIOLIB

Add __gpio_get_value()/__gpio_set_value() to fix compile error if
CONFIG_GPIOLIB = n.

Signed-off-by: Bob Liu <lliubbo@gmail.com>
diff --git a/arch/blackfin/include/asm/gpio.h b/arch/blackfin/include/asm/gpio.h
index 5a25856..12d3571 100644
--- a/arch/blackfin/include/asm/gpio.h
+++ b/arch/blackfin/include/asm/gpio.h
@@ -244,16 +244,26 @@
 	return -EINVAL;
 }
 
-static inline int gpio_get_value(unsigned gpio)
+static inline int __gpio_get_value(unsigned gpio)
 {
 	return bfin_gpio_get_value(gpio);
 }
 
-static inline void gpio_set_value(unsigned gpio, int value)
+static inline void __gpio_set_value(unsigned gpio, int value)
 {
 	return bfin_gpio_set_value(gpio, value);
 }
 
+static inline int gpio_get_value(unsigned gpio)
+{
+	return __gpio_get_value(gpio);
+}
+
+static inline void gpio_set_value(unsigned gpio, int value)
+{
+	return __gpio_set_value(gpio, value);
+}
+
 static inline int gpio_to_irq(unsigned gpio)
 {
 	if (likely(gpio < MAX_BLACKFIN_GPIOS))