use stream_packet and stream_sim from litex

liteeth/common.py

@@ -8,7 +8,7 @@ from litex.gen.genlib.fsm import FSM, NextState
 from litex.gen.genlib.misc import chooser, WaitTimer
 
 from litex.soc.interconnect.stream import *
-from litex.soc.interconnect.packet import *
+from litex.soc.interconnect.stream_packet import *
 from litex.soc.interconnect.csr import *