usb: imx21-hcd: make imx21_hc_driver const

Make this const as it is not modified anywhere.
Signed-off-by: NBhumika Goyal <bhumirks@gmail.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/usb/host/imx21-hcd.c

@@ -1779,7 +1779,7 @@ static void imx21_hc_stop(struct usb_hcd *hcd)
 /* Driver glue		 			*/
 /* =========================================== */
 
-static struct hc_driver imx21_hc_driver = {
+static const struct hc_driver imx21_hc_driver = {
 	.description = hcd_name,
 	.product_desc = "IMX21 USB Host Controller",
 	.hcd_priv_size = sizeof(struct imx21),