ixgbe: Modify 82599 HWRSC statistics counters

Divide 82599 HWRSC counters into aggregated and flushed to count number of
packets getting coalesced per TCP connection.

Signed-off-by: Mallikarjuna R Chilakala <mallikarjuna.chilakala@intel.com>
Acked-by: Peter P Waskiewicz Jr <peter.p.waskiewicz.jr@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>