Enable NEED_NETDEV for vendor command support.

The Vendor command needs to have the NEED_NETDEV internal flag set
for the corresponding vendor_cmd function to initialize correctly
and call the vendor subcommand specific doit function.

Change-Id: Icc46438dc9467fe0344cb832633c49466e2d20d0
CRs-fixed: 633799
Signed-off-by: Subhani Shaik <subhanis@codeaurora.org>