RDMA/irdma: Set VLAN in UD work completion correctly

Currently VLAN is reported in UD work completion when VLAN id is zero,
i.e. no VLAN case.

Report VLAN in UD work completion only when VLAN id is non-zero.

Fixes: b48c24c2

 ("RDMA/irdma: Implement device supported verb APIs")
Link: https://lore.kernel.org/r/20211019151654.1943-1-shiraz.saleem@intel.com
Signed-off-by: Mustafa Ismail <mustafa.ismail@intel.com>
Signed-off-by: Shiraz Saleem <shiraz.saleem@intel.com>
Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>