usb: gadget: udc: Drop surplus include

The UDC NET2272 driver includes <linux/gpio.h> but does not
use any symbols from this file, so drop the include.

Cc: Felipe Balbi <balbi@kernel.org>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Felipe Balbi <balbi@kernel.org>

drivers/usb/gadget/udc/net2272.c

@@ -9,7 +9,6 @@
 #include <linux/delay.h>
 #include <linux/device.h>
 #include <linux/errno.h>
-#include <linux/gpio.h>
 #include <linux/init.h>
 #include <linux/interrupt.h>
 #include <linux/io.h>