gpiolib: move gpiolib-sysfs function declarations into their own header

Move gpiolib-sysfs function declarations into their own header.

These functions are in gpiolib-sysfs.c, and are only required by gpiolib.c,
and so should be in a module header, not gpiolib.h.

This brings gpiolib-sysfs into line with gpiolib-cdev, and is another step
towards removing the sysfs inferface.

Signed-off-by: Kent Gibson <warthog618@gmail.com>
Signed-off-by: Bartosz Golaszewski <bgolaszewski@baylibre.com>
diff --git a/drivers/gpio/gpiolib-sysfs.c b/drivers/gpio/gpiolib-sysfs.c
index 82371fe..728f6c6 100644
--- a/drivers/gpio/gpiolib-sysfs.c
+++ b/drivers/gpio/gpiolib-sysfs.c
@@ -11,6 +11,7 @@
 #include <linux/ctype.h>
 
 #include "gpiolib.h"
+#include "gpiolib-sysfs.h"
 
 #define GPIO_IRQF_TRIGGER_FALLING	BIT(0)
 #define GPIO_IRQF_TRIGGER_RISING	BIT(1)