gpio: em: Use the right include

The Emma Mobile (EM) GPIO driver uses the too generic include
<linux/gpio.h>. It is a driver so it should just use
<linux/gpio/driver.h>.
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>

drivers/gpio/gpio-em.c

@@ -27,7 +27,7 @@
 #include <linux/irqdomain.h>
 #include <linux/bitops.h>
 #include <linux/err.h>
-#include <linux/gpio.h>
+#include <linux/gpio/driver.h>
 #include <linux/slab.h>
 #include <linux/module.h>
 #include <linux/pinctrl/consumer.h>