EthernetMessage: Fix TX receipts

Fixes
- HardwareEthernetPacket packing
- EthernetMessage::fcs

include/icsneo/communication/packet/ethernetpacket.h

@@ -10,6 +10,8 @@
 
 namespace icsneo {
 
+#pragma pack(push, 2)
+
 typedef uint16_t icscm_bitfield;
 
 struct HardwareEthernetPacket {
@@ -42,6 +44,8 @@ struct HardwareEthernetPacket {
 	uint16_t Length;
 };
 
+#pragma pack(pop)
+
 }
 
 #endif // __cplusplus