gpio: wm8xxx: Use the right header

These are GPIO drivers so just include <linux/gpio/driver.h>.

Cc: patches@opensource.cirrus.com
Cc: Charles Keepax <ckeepax@opensource.cirrus.com>
Cc: Mark Brown <broonie@kernel.org>
Acked-by: Richard Fitzgerald <rf@opensource.cirrus.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>

drivers/gpio/gpio-wm831x.c

@@ -15,7 +15,7 @@
 #include <linux/kernel.h>
 #include <linux/slab.h>
 #include <linux/module.h>
-#include <linux/gpio.h>
+#include <linux/gpio/driver.h>
 #include <linux/mfd/core.h>
 #include <linux/platform_device.h>
 #include <linux/seq_file.h>

drivers/gpio/gpio-wm8350.c

@@ -15,7 +15,7 @@
 #include <linux/kernel.h>
 #include <linux/slab.h>
 #include <linux/module.h>
-#include <linux/gpio.h>
+#include <linux/gpio/driver.h>
 #include <linux/mfd/core.h>
 #include <linux/platform_device.h>
 #include <linux/seq_file.h>

drivers/gpio/gpio-wm8994.c

@@ -15,7 +15,7 @@
 #include <linux/kernel.h>
 #include <linux/slab.h>
 #include <linux/module.h>
-#include <linux/gpio.h>
+#include <linux/gpio/driver.h>
 #include <linux/mfd/core.h>
 #include <linux/platform_device.h>
 #include <linux/seq_file.h>