Holger reported sporadic transmit timeouts and it turned out that one
path misses ringing the doorbell. Fix was suggested by Eric.
Fixes: ef14358546b1 ("r8169: make use of xmit_more") Suggested-by: Eric Dumazet <edumazet@google.com> Tested-by: Holger Hoffstätte <holger@applied-asynchrony.com> Signed-off-by: Heiner Kallweit <hkallweit1@gmail.com> Signed-off-by: David S. Miller <davem@davemloft.net>