skb_tx_timestamp() does not report software time stamp
if SKBTX_IN_PROGRESS is set. According to timestamping.txt
software time stamps are a fallback and should not be
generated if hardware time stamp is provided.

Move call to skb_tx_timestamp() after setting
SKBTX_IN_PROGRESS.
Signed-off-by: NJakub Kicinski <kubakici@wp.pl>
Tested-by: NAaron Brown <aaron.f.brown@intel.com>
Signed-off-by: NJeff Kirsher <jeffrey.t.kirsher@intel.com>