blackfin: gpio: Unreserve gpio in special_gpio_free()

In special_gpio_free(), call unreserve() rather than reserve() to release gpio.

Signed-off-by: Axel Lin <axel.lin@ingics.com>
Signed-off-by: Sonic Zhang <sonic.zhang@analog.com>

arch/blackfin/cpu/gpio.c

@@ -662,8 +662,8 @@ void special_gpio_free(unsigned gpio)
 		return;
 	}
 
-	reserve(special_gpio, gpio);
-	reserve(peri, gpio);
+	unreserve(special_gpio, gpio);
+	unreserve(peri, gpio);
 	set_label(gpio, "free");
 }
 #endif