ice: Fix transmit for all software offloaded VLANs

ice: Fix transmit for all software offloaded VLANs

Currently the driver does not recognize when there is an 802.1AD VLAN
tag right after the dmac/smac (outermost VLAN tag). If any DCB map is
applied and/or DCB is enabled this is causing the hardware to insert a
VLAN 0 tag after the 802.1AD VLAN tag that is already in the packet.
Fix this by preventing VLAN tag 0 from being added when any VLAN is
already present after dmac/smac (software offloaded) or skb (hardware
offloaded).

Signed-off-by: Brett Creeley <brett.creeley@intel.com>
Tested-by: Andrew Bowers <andrewx.bowers@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>