rfkill: gpio: Remove unused include

The legacy <linux/gpio.h> header is no longer in use by the
rfkill driver, so drop this include.
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Johannes Berg <johannes.berg@intel.com>

net/rfkill/rfkill-gpio.c

@@ -16,7 +16,6 @@
  * 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
  */
 
-#include <linux/gpio.h>
 #include <linux/init.h>
 #include <linux/kernel.h>
 #include <linux/module.h>