net:ethernet:aquantia: Workaround for HW checksum bug.

The hardware has the HW Checksum Offload bug when small
TCP patckets (with length <= 60 bytes) has wrong "checksum valid" bit.

The solution is - ignore checksum valid bit for small packets
(with length <= 60 bytes) and mark this as CHECKSUM_NONE to allow
network stack recalculate checksum itself.

Fixes: ccf9a5ed14be ("net: ethernet: aquantia: Atlantic A0 and B0 specific functions.")
Signed-off-by: Pavel Belous <Pavel.Belous@aquantia.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/ethernet/aquantia/atlantic/hw_atl/hw_atl_a0.c

@@ -629,6 +629,12 @@ static int hw_atl_a0_hw_ring_rx_receive(struct aq_hw_s *self,
 				buff->is_udp_cso = (is_err & 0x10U) ? 0 : 1;
 			else if (0x0U == (pkt_type & 0x1CU))
 				buff->is_tcp_cso = (is_err & 0x10U) ? 0 : 1;
+
+			/* Checksum offload workaround for small packets */
+			if (rxd_wb->pkt_len <= 60) {
+				buff->is_ip_cso = 0U;
+				buff->is_cso_err = 0U;
+			}
 		}
 
 		is_err &= ~0x18U;

drivers/net/ethernet/aquantia/atlantic/hw_atl/hw_atl_b0.c

@@ -645,6 +645,12 @@ static int hw_atl_b0_hw_ring_rx_receive(struct aq_hw_s *self,
 				buff->is_udp_cso = buff->is_cso_err ? 0U : 1U;
 			else if (0x0U == (pkt_type & 0x1CU))
 				buff->is_tcp_cso = buff->is_cso_err ? 0U : 1U;
+
+			/* Checksum offload workaround for small packets */
+			if (rxd_wb->pkt_len <= 60) {
+				buff->is_ip_cso = 0U;
+				buff->is_cso_err = 0U;
+			}
 		}
 
 		is_err &= ~0x18U;