liteeth/phy: rename rgmii to s6rgmii since specific to Spartan6

Also remove autodetection support for RGMII. For it to work we would need to pass the device we are building for.

misoclib/com/liteeth/phy/__init__.py

@@ -17,9 +17,8 @@ def LiteEthPHY(clock_pads, pads, **kwargs):
             from misoclib.com.liteeth.phy.gmii import LiteEthPHYGMII
             return LiteEthPHYGMII(clock_pads, pads, **kwargs)
     elif hasattr(pads, "rx_ctl"):
-         # This is a 10/100/1G RGMII PHY
-           from misoclib.com.liteeth.phy.rgmii import LiteEthPHYRGMII
-           return LiteEthPHYRGMII(clock_pads, pads, **kwargs)
+        # This is a 10/100/1G RGMII PHY
+        raise ValueError("RGMII PHYs are specific to vendors (for now), use direct instantiation")
     elif flen(pads.tx_data) == 4:
         # This is a MII PHY
         from misoclib.com.liteeth.phy.mii import LiteEthPHYMII

misoclib/com/liteeth/phy/s6rgmii.py

@@ -1,3 +1,5 @@
+# RGMII PHY for Spartan-6
+
 from migen.genlib.io import DDROutput
 from migen.genlib.misc import WaitTimer
 from migen.genlib.fsm import FSM, NextState