of/gpio: fix of_gpio includes

drivers/of/gpio.c is missing includes for of_irq and struct device which
cause build failures on ARM.  This patch adds the correct include files
and removes the unneeded kernel.h include
Signed-off-by: Grant Likely <grant.likely@secretlab.ca>

drivers/of/gpio.c

@@ -11,13 +11,14 @@
  * (at your option) any later version.
  */
 
-#include <linux/kernel.h>
+#include <linux/device.h>
 #include <linux/errno.h>
+#include <linux/module.h>
 #include <linux/io.h>
 #include <linux/of.h>
-#include <linux/slab.h>
+#include <linux/of_address.h>
 #include <linux/of_gpio.h>
-#include <asm/prom.h>
+#include <linux/slab.h>
 
 /**
  * of_get_gpio_flags - Get a GPIO number and flags to use with GPIO API