mfd: asic3: Include the right header

This is a GPIO driver, use the appropriate header
<linux/gpio/driver.h> rather than the legacy <linux/gpio.h>
header.
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Lee Jones <lee.jones@linaro.org>

drivers/mfd/asic3.c

@@ -15,7 +15,7 @@
 #include <linux/kernel.h>
 #include <linux/delay.h>
 #include <linux/irq.h>
-#include <linux/gpio.h>
+#include <linux/gpio/driver.h>
 #include <linux/export.h>
 #include <linux/io.h>
 #include <linux/slab.h>