i40e: add counter for arq overflows

Sometimes, ARQ overflows are a big deal and tell us that the
firmware/hardware/driver/something is having problems. But normally
they're no big deal. To assist in assessing this, add a counter to
our Ethtool stats. A handful of ARQ overflows during VF init is no
problem. A large, ever-growing number indicates that Something Bad is
happening.

Change-ID: Ie5348bfbc8a54a890559cb00279c28d976a55096
Signed-off-by: Mitch Williams <mitch.a.williams@intel.com>
Tested-by: Andrew Bowers <andrewx.bowers@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>
diff --git a/drivers/net/ethernet/intel/i40e/i40e_ethtool.c b/drivers/net/ethernet/intel/i40e/i40e_ethtool.c
index 4549591..812c954 100644
--- a/drivers/net/ethernet/intel/i40e/i40e_ethtool.c
+++ b/drivers/net/ethernet/intel/i40e/i40e_ethtool.c
@@ -143,6 +143,7 @@
 	I40E_PF_STAT("rx_oversize", stats.rx_oversize),
 	I40E_PF_STAT("rx_jabber", stats.rx_jabber),
 	I40E_PF_STAT("VF_admin_queue_requests", vf_aq_requests),
+	I40E_PF_STAT("arq_overflows", arq_overflows),
 	I40E_PF_STAT("rx_hwtstamp_cleared", rx_hwtstamp_cleared),
 	I40E_PF_STAT("fdir_flush_cnt", fd_flush_cnt),
 	I40E_PF_STAT("fdir_atr_match", stats.fd_atr_match),