Add support nat zone setting for VLAN sub interfaces.

[iMasaruOki]

Signed-off-by: Masaru OKI [email protected]

What I did

Add support VLAN sub interfaces (e.g. Ethernet0.100) for 'config nat add interface'.

How I did it

VLAN sub interface configuration is checked in interface name validation.

How to verify it

# on nat enabled images
sudo config interface ip add Ethernet0.100 192.168.0.1/24
sudo config nat add interface -nat_zone 0 Ethernet0.100

Previous command output (if the output of a command-line utility has changed)

Usage: config nat add interface [OPTIONS] <interface_name>
Try "config nat add interface -h" for help.

Error: Interface name is invalid. Please enter a  valid interface name!!

New command output (if the output of a command-line utility has changed)

empty output