Input: wacom_i2c - remove unneeded gpio.h header file

There is no gpio functions used in the driver that is exported
by the gpio.h header, so remove this unneeded header.
Signed-off-by: Fabio Estevam <festevam@gmail.com>
Link: https://lore.kernel.org/r/20191026185958.24158-3-festevam@gmail.comSigned-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>

drivers/input/touchscreen/wacom_i2c.c

@@ -12,7 +12,6 @@
 #include <linux/slab.h>
 #include <linux/irq.h>
 #include <linux/interrupt.h>
-#include <linux/gpio.h>
 #include <asm/unaligned.h>
 
 #define WACOM_CMD_QUERY0	0x04