wgengine/magicsock: delete unused WhoIs method that was moved elsewhere

Signed-off-by: Brad Fitzpatrick <bradfitz@tailscale.com>

wgengine/magicsock/magicsock.go

@@ -3789,25 +3789,6 @@ func (de *discoEndpoint) numStopAndReset() int64 {
 // derpStr replaces DERP IPs in s with "derp-".
 func derpStr(s string) string { return strings.ReplaceAll(s, "127.3.3.40:", "derp-") }
 
-// WhoIs reports the node and user who owns the node with the given IP.
-// If ok == true, n and u are valid.
-func (c *Conn) WhoIs(ip netaddr.IP) (n *tailcfg.Node, u tailcfg.UserProfile, ok bool) {
-	c.mu.Lock()
-	defer c.mu.Unlock()
-	if c.netMap == nil {
-		return n, u, false
-	}
-	for _, p := range c.netMap.Peers {
-		for _, ipp := range p.Addresses {
-			if ipp.IsSingleIP() && ipp.IP == ip {
-				u, ok := c.netMap.UserProfiles[p.User]
-				return p, u, ok
-			}
-		}
-	}
-	return nil, u, false
-}
-
 // ippEndpointCache is a mutex-free single-element cache, mapping from
 // a single netaddr.IPPort to a single endpoint.
 type ippEndpointCache struct {