wgengine/magicsock: fix typo in Conn.handlePingLocked() (#10365)

Updates #cleanup

Signed-off-by: Jordan Whited <jordan@tailscale.com>

wgengine/magicsock/magicsock.go

@@ -1514,7 +1514,7 @@ func (c *Conn) handlePingLocked(dm *disco.Ping, src netip.AddrPort, di *discoInf
 	// mappings to make p2p path discovery faster in simple
 	// cases. Without this, disco would still work, but would be
 	// reliant on DERP call-me-maybe to establish the disco<>node
-	// mapping, and on subsequent disco handlePongLocked to establish
+	// mapping, and on subsequent disco handlePongConnLocked to establish
 	// the IP<>disco mapping.
 	if nk, ok := c.unambiguousNodeKeyOfPingLocked(dm, di.discoKey, derpNodeSrc); ok {
 		if !isDerp {