gpiolib: remove duplicated include from gpiolib.c

Remove duplicated include.
Signed-off-by: Wei Yongjun <yongjun_wei@trendmicro.com.cn>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>

drivers/gpio/gpiolib.c

@@ -16,7 +16,6 @@
 #include <linux/gpio/driver.h>
 #include <linux/gpio/machine.h>
 #include <linux/pinctrl/consumer.h>
-#include <linux/idr.h>
 #include <linux/cdev.h>
 #include <linux/fs.h>
 #include <linux/uaccess.h>