wireless: T1627: support station mode
wireless: T1627: support station mode

Tested using:
-------------

set interfaces wireless wlan0 address 'dhcp'
set interfaces wireless wlan0 channel '0'
set interfaces wireless wlan0 description '1'
set interfaces wireless wlan0 physical-device 'phy0'
set interfaces wireless wlan0 security wpa passphrase '12345678'
set interfaces wireless wlan0 ssid 'VyOS-TEST'
set interfaces wireless wlan0 type 'station'

vyos/vyos-1x,vyos/vyos-1x,vyos/vyos-1x,vyos/vyos-1x