system: T6193: invalid warning "is not a DHCP interface but uses DHCP name-server option"
This fixes an invalid warning when using a DHCP VLAN interface to retrieve the
system nameserver to be used. VLAN CLI config is not properly expanded
leading to a false warning:
[ system name-server eth1.10 ]
WARNING: "eth1.10" is not a DHCP interface but uses DHCP name-server option!
(cherry picked from commit 61e70c5500ad5b0a9d25bdee28d982644bad6461)