backlight: ams369fg06: Drop GPIO include

The driver includes <linux/gpio.h> yet fails to use symbols
from any the header so drop the include.
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
Reviewed-by: Daniel Thompson <daniel.thompson@linaro.org>
Signed-off-by: Lee Jones <lee.jones@linaro.org>

drivers/video/backlight/ams369fg06.c

@@ -11,7 +11,6 @@
 #include <linux/backlight.h>
 #include <linux/delay.h>
 #include <linux/fb.h>
-#include <linux/gpio.h>
 #include <linux/lcd.h>
 #include <linux/module.h>
 #include <linux/spi/spi.h>