RDMA/bnxt_re: Check if the vlan is valid before reporting

When VF is configured with default vlan, HW strips the vlan from the
packet and driver receives it in Rx completion. VLAN needs to be reported
for UD work completion only if the vlan is configured on the host. Add a
check for valid vlan in the UD receive path.

Link: https://lore.kernel.org/r/1631709163-2287-12-git-send-email-selvin.xavier@broadcom.com
Signed-off-by: Selvin Xavier <selvin.xavier@broadcom.com>
Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>