phy: add KUSDDRPHY to __init__.py

litedram/phy/__init__.py

@@ -1,6 +1,7 @@
 from litedram.phy.gensdrphy import GENSDRPHY
 from litedram.phy.s6ddrphy import S6HalfRateDDRPHY, S6QuarterRateDDRPHY
 from litedram.phy.s7ddrphy import V7DDRPHY, K7DDRPHY, A7DDRPHY
+from litedram.phy.kusddrphy import KUSDDRPHY
 
 # backward compatibility (remove when no longer needed)
 from litedram.phy import s7ddrphy as a7ddrphy