r8169: fix early queue wake-up.

[ Upstream commit ae1f23fb433ac0aaff8aeaa5a7b14348e9aa8277 ]

With infinite gratitude to Eric Dumazet for allowing me to identify
the error.

Signed-off-by: Francois Romieu <romieu@fr.zoreil.com>
Acked-by: Eric Dumazet <eric.dumazet@gmail.com>
Cc: Hayes Wang <hayeswang@realtek.com>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>