Implemented getvdb
* Functions that use getvdb must initialise an array bitmap of SW_VLAN_BMP_NO elements
* getvdb gets the entire vlan bitmap. If you are interested in a specific vlan you must iterate through the whole bitmap.
* In order to test the function you must also get the last switch kernel module

Signed-off-by: Duta Victor Marin <duta.victor.marin@gmail.com>