VLAN assignment based on used WPA/WPA2 passphrase/PSK

VLAN assignment based on used WPA/WPA2 passphrase/PSK

Extend wpa_psk_file to allow an optional VLAN ID to be specified with
"vlanid=<VLAN ID>" prefix on the line. If VLAN ID is specified and the
particular wpa_psk_file entry is used for a station, that station is
bound to the specified VLAN. This can be used to operate a single
WPA2-Personal BSS with multiple VLANs based on the used passphrase/PSK.
This is similar to the WPA2-Enterprise case where the RADIUS server can
assign stations to different VLANs.

Signed-off-by: Jouni Malinen <jouni@codeaurora.org>