USB: ehci-spear: Make of_device_id array const

Make of_device_id array const, because all OF functions handle
it as const.
Signed-off-by: NJingoo Han <jg1.han@samsung.com>
Acked-by: NViresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/usb/host/ehci-spear.c

@@ -150,7 +150,7 @@ static int spear_ehci_hcd_drv_remove(struct platform_device *pdev)
 	return 0;
 }
 
-static struct of_device_id spear_ehci_id_table[] = {
+static const struct of_device_id spear_ehci_id_table[] = {
 	{ .compatible = "st,spear600-ehci", },
 	{ },
 };