HID: steam: Constify lowlevel HID driver

Since commit 52d22534 ("HID: Make lowlevel driver structs const")
the lowlevel HID drivers are only exposed as const.

Take advantage of this to constify the underlying structure, too.
Signed-off-by: Thomas Weißschuh <linux@weissschuh.net>
Reviewed-by: Hans de Goede <hdegoede@redhat.com>
Link: https://lore.kernel.org/r/20230130-hid-const-ll-driver-v1-4-3fc282b3b1d0@weissschuh.netSigned-off-by: Benjamin Tissoires <benjamin.tissoires@redhat.com>

drivers/hid/hid-steam.c

@@ -674,7 +674,7 @@ static int steam_client_ll_raw_request(struct hid_device *hdev,
 			report_type, reqtype);
 }
 
-static struct hid_ll_driver steam_client_ll_driver = {
+static const struct hid_ll_driver steam_client_ll_driver = {
 	.parse = steam_client_ll_parse,
 	.start = steam_client_ll_start,
 	.stop = steam_client_ll_stop,