e1000e: balance semaphore put/get for 82573

Steven (cc-ed) noticed an imbalance in semaphore put/get for
82573-based NICs. Don't we need something like the following
(untested) patch?

Signed-off-by: Steven La <sla@riverbed.com>
Acked-by: Arthur Kepner <akepner@riverbed.com>
Tested-by: Aaron Brown <aaron.f.brown@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>