r8169: fix network stalls due to missing bit TXCFG_AUTO_FIFO

Some of the chip-specific hw_start functions set bit TXCFG_AUTO_FIFO
in register TxConfig. The original patch changed the order of some
calls resulting in these changes being overwritten by
rtl_set_tx_config_registers() in rtl_hw_start(). This eventually
resulted in network stalls especially under high load.

Analyzing the chip-specific hw_start functions all chip version from
34, with the exception of version 39, need this bit set.
This patch moves setting this bit to rtl_set_tx_config_registers().

Fixes: 4fd48c4a ("r8169: move common initializations to tp->hw_start")
Reported-by: Ortwin Glück <odi@odi.ch>
Reported-by: David Arendt <admin@prnet.org>
Root-caused-by: Maciej S. Szmigiero <mail@maciej.szmigiero.name>
Tested-by: Tony Atkinson <tatkinson@linux.com>
Tested-by: David Arendt <admin@prnet.org>
Tested-by: Ortwin Glück <odi@odi.ch>
Signed-off-by: Heiner Kallweit <hkallweit1@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>