fix(dronecan): send elapsed ms since last seen in MSP2_INAV_DRONECAN_NODE_INFO

Apply the same fix as MSP2_INAV_DRONECAN_NODES: send millis() - last_seen_ms
so the field means elapsed time since last heard from the node.

Author: daijoubu

src/main/fc/fc_msp.c

@@ -4605,7 +4605,7 @@ bool mspFCProcessInOutCommand(uint16_t cmdMSP, sbuf_t *dst, sbuf_t *src, mspResu
                     sbufWriteU8(dst, node->mode);
                     sbufWriteU32(dst, node->uptime_sec);
                     sbufWriteU16(dst, node->vendor_status_code);
-                    sbufWriteU32(dst, node->last_seen_ms);
+                    sbufWriteU32(dst, millis() - node->last_seen_ms);
                     sbufWriteU8(dst, node->name_len);
                     sbufWriteDataSafe(dst, node->name, 32);
                     found = true;