util: allow retrieving ethtool features when unprivileged

The only reason that the ethtool features weren't being retrieved in
an unprivileged libvirtd was because they required ioctl(), and the
ioctl was using an AF_PACKET socket, which requires root. Now that we
are using AF_UNIX for ioctl(), this restriction can be removed.

src/util/virnetdev.c

@@ -2583,12 +2583,6 @@ virNetDevGetFeatures(const char *ifname,
     if (!(*out = virBitmapNew(VIR_NET_DEV_FEAT_LAST)))
         return -1;
 
-    /* Only fetch features if we're privileged, but no need to fail */
-    if (geteuid() != 0) {
-        VIR_DEBUG("ETHTOOL feature bits not available in session mode");
-        return 0;
-    }
-
     if ((fd = virNetDevSetupControl(ifname, &ifr)) < 0)
         goto cleanup;