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: Jingoo Han <[e-mail]>
Acked-by: Viresh Kumar <[e-mail]>
Signed-off-by: Greg Kroah-Hartman <[e-mail]>

drivers/usb/host/ehci-spear.c

···
 	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", },
 	{ },
 };