Part of virtchannel messages are treated in different way in switchdev
mode to block configuring VFs from iavf driver side. This blocking was
done by doing nothing and returning success, event without sending
response.

Not sending response for opcodes that aren't supported in switchdev mode
leads to block iavf driver message handling. This happens for example
when vlan is configured at VF config time (VLAN module is already
loaded).

To get rid of it ice driver should answer for each VF message. In
switchdev mode:
- for adding/deleting VLAN driver should answer success without doing
  anything to allow creating vlan device on VFs
- for enabling/disabling VLAN stripping  and promiscuous mode driver
  should answer not supported, this feature in switchdev can be only
  set from host side
Signed-off-by: Michal Swiatkowski <michal.swiatkowski@linux.intel.com>
Tested-by: Sandeep Penigalapati <sandeep.penigalapati@intel.com>
Signed-off-by: Tony Nguyen <anthony.l.nguyen@intel.com>