usb: gadget/snps_udc_plat: Remove unused of_gpio.h

of_gpio.h is deprecated and subject to remove.
The driver doesn't use it, simply remove the unused header.
Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Link: https://lore.kernel.org/r/20240307112509.3627937-1-andriy.shevchenko@linux.intel.comSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/usb/gadget/udc/snps_udc_plat.c

@@ -8,7 +8,6 @@
 #include <linux/extcon.h>
 #include <linux/of_address.h>
 #include <linux/of_irq.h>
-#include <linux/of_gpio.h>
 #include <linux/platform_device.h>
 #include <linux/phy/phy.h>
 #include <linux/module.h>