e1000e: Be drop monitor friendly

e1000e: Be drop monitor friendly

e1000e_put_txbuf() can be called from normal reclamation path as well as
when a DMA mapping failure, so we need to differentiate these two cases
when freeing SKBs to be drop monitor friendly. e1000e_tx_hwtstamp_work()
and e1000_remove() are processing TX timestamped SKBs and those should
not be accounted as drops either.

Signed-off-by: Florian Fainelli <f.fainelli@gmail.com>
Tested-by: Aaron Brown <aaron.f.brown@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>
Orabug: 27069012
(cherry picked from commit 377b62736c01f14309141c69caa6d84363c12e12)
Signed-off-by: Jack Vogel <jack.vogel@oracle.com>
Reviewed-by: Ethan Zhao <ethan.zhao@oracle.com>