Fix LINT build

[lwhsu]

Summary

r328377 seems breaking LINT build:

https://ci.freebsd.org/job/FreeBSD-head-amd64-LINT/6419/console

00:02:45.818 --- rtl8366rb.o ---
00:02:45.818 /workspace/src/sys/dev/etherswitch/rtl8366/rtl8366rb.c:243:22: error: no member named 'sc_dev' in 'struct rtl8366rb_softc'
00:02:45.818                         device_printf(sc->sc_dev, "couldn't allocate ifnet structure\n");
00:02:45.818                                       ~~  ^
00:02:45.827 1 error generated.
00:02:45.830 *** [rtl8366rb.o] Error code 1
00:02:45.830
00:02:45.830 make[2]: stopped in /workspace/obj/workspace/src/amd64.amd64/sys/LINT