fm10k: move setting shinfo inside ts_tx_enqueue

This patch simplifies the code flow for setting the IN_PROGRESS bit of
the shinfo for an skb we will be timestamping.

Reported-by: Eric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: Jacob Keller <jacob.e.keller@intel.com>
Tested-by: Krishneil Singh <Krishneil.k.singh@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>