drm/dp_mst: Cleanup drm_dp_send_link_address() a bit

Declare local pointer to the drm_dp_link_address_ack_reply struct
instead of constantly dereferencing it through the union in
txmsg->reply. Also rearrange variable declarations a bit.

Signed-off-by: Lyude Paul <lyude@redhat.com>

drivers/gpu/drm/drm_dp_mst_topology.c

@@ -2033,9 +2033,9 @@ drm_dp_dump_link_address(struct drm_dp_link_address_ack_reply *reply)
 static void drm_dp_send_link_address(struct drm_dp_mst_topology_mgr *mgr,
 				     struct drm_dp_mst_branch *mstb)
 {
-	int len;
 	struct drm_dp_sideband_msg_tx *txmsg;
-	int ret;
+	struct drm_dp_link_address_ack_reply *reply;
+	int len, ret;
 
 	txmsg = kzalloc(sizeof(*txmsg), GFP_KERNEL);
 	if (!txmsg)
@@ -2054,13 +2054,16 @@ static void drm_dp_send_link_address(struct drm_dp_mst_topology_mgr *mgr,
 		if (txmsg->reply.reply_type == DP_SIDEBAND_REPLY_NAK) {
 			DRM_DEBUG_KMS("link address nak received\n");
 		} else {
-			DRM_DEBUG_KMS("link address reply: %d\n", txmsg->reply.u.link_addr.nports);
-			drm_dp_dump_link_address(&txmsg->reply.u.link_addr);
+			reply = &txmsg->reply.u.link_addr;
+			DRM_DEBUG_KMS("link address reply: %d\n",
+				      reply->nports);
+			drm_dp_dump_link_address(reply);
 
-			drm_dp_check_mstb_guid(mstb, txmsg->reply.u.link_addr.guid);
+			drm_dp_check_mstb_guid(mstb, reply->guid);
 
-			for (i = 0; i < txmsg->reply.u.link_addr.nports; i++) {
-				drm_dp_add_port(mstb, mgr->dev, &txmsg->reply.u.link_addr.ports[i]);
+			for (i = 0; i < reply->nports; i++) {
+				drm_dp_add_port(mstb, mgr->dev,
+						&reply->ports[i]);
 			}
 			drm_kms_helper_hotplug_event(mgr->dev);
 		}