staging: greybus: arche-apb-ctrl: declare struct of_device_id as const

Declare the 'arche_apb_ctrl_of_match' array as const. This array is only stored
in the .of_match_table field of a device_driver structure, which is declared as
const. This addresses the checkpatch warning:

WARNING: struct of_device_id should be normally const
Signed-off-by: Eva Rachel Retuya <eraretuya@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/staging/greybus/arche-apb-ctrl.c

@@ -495,7 +495,7 @@ static void arche_apb_ctrl_shutdown(struct platform_device *pdev)
 static SIMPLE_DEV_PM_OPS(arche_apb_ctrl_pm_ops, arche_apb_ctrl_suspend,
 			 arche_apb_ctrl_resume);
 
-static struct of_device_id arche_apb_ctrl_of_match[] = {
+static const struct of_device_id arche_apb_ctrl_of_match[] = {
 	{ .compatible = "usbffff,2", },
 	{ },
 };