ixgbe: add /* fallthrough */ comment to case statements

This semicomplex switch-case has various fallthrough portions, that were
not indicated by a /* fallthrough */ comment.
Signed-off-by: Jacob Keller <jacob.e.keller@intel.com>
Tested-by: Phil Schmitt <phillip.j.schmitt@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>

drivers/net/ethernet/intel/ixgbe/ixgbe_ethtool.c

@@ -2415,9 +2415,11 @@ static int ixgbe_get_rss_hash_opts(struct ixgbe_adapter *adapter,
 	switch (cmd->flow_type) {
 	case TCP_V4_FLOW:
 		cmd->data |= RXH_L4_B_0_1 | RXH_L4_B_2_3;
+		/* fallthrough */
 	case UDP_V4_FLOW:
 		if (adapter->flags2 & IXGBE_FLAG2_RSS_FIELD_IPV4_UDP)
 			cmd->data |= RXH_L4_B_0_1 | RXH_L4_B_2_3;
+		/* fallthrough */
 	case SCTP_V4_FLOW:
 	case AH_ESP_V4_FLOW:
 	case AH_V4_FLOW:
@@ -2427,9 +2429,11 @@ static int ixgbe_get_rss_hash_opts(struct ixgbe_adapter *adapter,
 		break;
 	case TCP_V6_FLOW:
 		cmd->data |= RXH_L4_B_0_1 | RXH_L4_B_2_3;
+		/* fallthrough */
 	case UDP_V6_FLOW:
 		if (adapter->flags2 & IXGBE_FLAG2_RSS_FIELD_IPV6_UDP)
 			cmd->data |= RXH_L4_B_0_1 | RXH_L4_B_2_3;
+		/* fallthrough */
 	case SCTP_V6_FLOW:
 	case AH_ESP_V6_FLOW:
 	case AH_V6_FLOW: