rockchip64-6.18: typec dp extcon: fix clang -Wincompatible-pointer-types-discards-qualifiers

extcon_get_edev_by_phandle() takes struct device * (non-const), but
the patch declared the local as const struct device *. Drop the const:
&dp->alt->dev is a non-const pointer anyway, and the 7.1/7.2 copies of
this patch already use the non-const form.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

Author: iav

patch/kernel/archive/rockchip64-6.18/rk3399-usbc-notify-typec-dp-hpd-state-through-extcon.patch

@@ -31,7 +31,7 @@ index 111111111111..222222222222 100644
 +/* Notify DP hotplug change via extcon. Current rockchip cdn-dp driver need this signal
 + * to reset DP link. */
 +static void dp_altmode_update_extcon_hpd_status(struct dp_altmode *dp, bool new_hpd) {
-+	const struct device *dev = &dp->alt->dev;
++	struct device *dev = &dp->alt->dev;
 +	struct extcon_dev* edev = NULL;
 +	int ret;
 +