RDMA/qedr: Parse VLAN ID correctly and ignore the value of zero

Rename vlan_id field name to vlan as it contains more than the vlan_id.
Mask out non vlan id fields from vlan tag of the QED LL2 RX GSI
vlan output. As it is expected to be vlan id only.
Ignore vlan_id with value of zero.

Fixes: abd49676 ("qed: Add RoCE ll2 & GSI support")
Signed-off-by: Ram Amrani <Ram.Amrani@cavium.com>
Signed-off-by: Michal Kalderon <Michal.Kalderon@cavium.com>
Signed-off-by: Doug Ledford <dledford@redhat.com>