usb: typec: fusb302: mark OF related data as maybe unused

The driver can be compile tested with !CONFIG_OF making certain data
unused:

  drivers/usb/typec/tcpm/fusb302.c:1816:34: error: ‘fusb302_dt_match’ defined but not used [-Werror=unused-const-variable=]
Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Reviewed-by: Heikki Krogerus <heikki.krogerus@linux.intel.com>
Reviewed-by: Guenter Roeck <linux@roeck-us.net>
Link: https://lore.kernel.org/r/20230310222937.315773-2-krzysztof.kozlowski@linaro.orgSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/usb/typec/tcpm/fusb302.c

@@ -1813,7 +1813,7 @@ static int fusb302_pm_resume(struct device *dev)
 	return 0;
 }
 
-static const struct of_device_id fusb302_dt_match[] = {
+static const struct of_device_id fusb302_dt_match[] __maybe_unused = {
 	{.compatible = "fcs,fusb302"},
 	{},
 };