txphy: update comment: RTL8139 -> TNETE2101

[Kevin Lo]

ok?

Index: sys/dev/mii/txphy.c
===================================================================
RCS file: /cvs/src/sys/dev/mii/txphy.c,v
retrieving revision 1.12
diff -u -p -u -p -r1.12 txphy.c
--- sys/dev/mii/txphy.c 6 Apr 2022 18:59:29 -0000       1.12
+++ sys/dev/mii/txphy.c 29 Mar 2023 08:05:27 -0000
@@ -114,7 +114,7 @@ txphy_service(struct mii_softc *sc, stru
                return (ENXIO);
 
        /*
-        * Can't isolate the RTL8139 phy, so it has to be the only one.
+        * Can't isolate the TNETE2101 phy, so it has to be the only one.
         */
        if (IFM_INST(ife->ifm_media) != sc->mii_inst)
                panic("txphy_service: attempt to isolate phy");