core: allow interface altnames in RestrictNetworkInterfaces=

This patch enables IFNAME_VALID_ALTERNATIVE for checks guarding the
parsing of RestrictNetworkInterfaces=.

The underlying implementation for this option already supports
altnames.

src/core/dbus-cgroup.c

@@ -2188,7 +2188,7 @@ int bus_cgroup_set_property(
                                 c->restrict_network_interfaces_is_allow_list = is_allow_list;
 
                         STRV_FOREACH(s, l) {
-                                if (!ifname_valid(*s)) {
+                                if (!ifname_valid_full(*s, IFNAME_VALID_ALTERNATIVE)) {
                                         log_full(LOG_WARNING, "Invalid interface name, ignoring: %s", *s);
                                         continue;
                                 }

src/core/load-fragment.c

@@ -6096,7 +6096,7 @@ int config_parse_restrict_network_interfaces(
                         break;
                 }
 
-                if (!ifname_valid(word)) {
+                if (!ifname_valid_full(word, IFNAME_VALID_ALTERNATIVE)) {
                         log_syntax(unit, LOG_WARNING, filename, line, 0, "Invalid interface name, ignoring: %s", word);
                         continue;
                 }