net: macb: Reset TX when TX halt times out

Reset TX when halt times out i.e. disable TX, clean up TX BDs,
interrupts (already done) and enable TX.
This addresses the issue observed when iperf is run at 10Mps Half
duplex where, after multiple collisions and retries, TX halts.

Signed-off-by: Harini Katakam <harini.katakam@xilinx.com>
Signed-off-by: Michal Simek <michal.simek@xilinx.com>
Signed-off-by: Radhey Shyam Pandey <radhey.shyam.pandey@xilinx.com>
Reviewed-by: Michal Swiatkowski <michal.swiatkowski@linux.intel.com>
Acked-by: Nicolas Ferre <nicolas.ferre@microchip.com>
Signed-off-by: David S. Miller <davem@davemloft.net>