net/ice/base: add interface to support configuring VLAN mode

net/ice/base: add interface to support configuring VLAN mode

The VLAN mode of the device has to be configured while the global
configuration lock is held while downloading the DDP, specifically after
the DDP has been downloaded. In order to support this a VLAN mode
interface was added. By default the device will stay in single VLAN
mode (SVM), which is the current implementation. However, this can be
changed by implementing the .set_dvm op.

Signed-off-by: Brett Creeley <brett.creeley@intel.com>
Signed-off-by: Qi Zhang <qi.z.zhang@intel.com>
Acked-by: Qiming Yang <qiming.yang@intel.com>