igc: Early return in igc_get_ethtool_nfc_entry()

This patch re-writes the second half of igc_ethtool_get_nfc_entry() to
follow the 'return early' pattern seen in other parts of the driver and
removes some duplicate comments.
Signed-off-by: Andre Guedes <andre.guedes@intel.com>
Tested-by: Aaron Brown <aaron.f.brown@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>

drivers/net/ethernet/intel/igc/igc_ethtool.c

@@ -945,38 +945,36 @@ static int igc_get_ethtool_nfc_entry(struct igc_adapter *adapter,
 	if (!rule || fsp->location != rule->sw_idx)
 		return -EINVAL;
 
-	if (rule->filter.match_flags) {
+	if (!rule->filter.match_flags)
+		return -EINVAL;
+
 	fsp->flow_type = ETHER_FLOW;
 	fsp->ring_cookie = rule->action;
+
 	if (rule->filter.match_flags & IGC_FILTER_FLAG_ETHER_TYPE) {
 		fsp->h_u.ether_spec.h_proto = rule->filter.etype;
 		fsp->m_u.ether_spec.h_proto = ETHER_TYPE_FULL_MASK;
 	}
+
 	if (rule->filter.match_flags & IGC_FILTER_FLAG_VLAN_TCI) {
 		fsp->flow_type |= FLOW_EXT;
 		fsp->h_ext.vlan_tci = rule->filter.vlan_tci;
 		fsp->m_ext.vlan_tci = htons(VLAN_PRIO_MASK);
 	}
+
 	if (rule->filter.match_flags & IGC_FILTER_FLAG_DST_MAC_ADDR) {
 		ether_addr_copy(fsp->h_u.ether_spec.h_dest,
 				rule->filter.dst_addr);
-			/* As we only support matching by the full
-			 * mask, return the mask to userspace
-			 */
 		eth_broadcast_addr(fsp->m_u.ether_spec.h_dest);
 	}
+
 	if (rule->filter.match_flags & IGC_FILTER_FLAG_SRC_MAC_ADDR) {
 		ether_addr_copy(fsp->h_u.ether_spec.h_source,
 				rule->filter.src_addr);
-			/* As we only support matching by the full
-			 * mask, return the mask to userspace
-			 */
 		eth_broadcast_addr(fsp->m_u.ether_spec.h_source);
 	}
 
 	return 0;
-	}
-	return -EINVAL;
 }
 
 static int igc_get_ethtool_nfc_all(struct igc_adapter *adapter,