net/mlx5e: Use custom tunnel header for vxlan gbp

Symbolic (e.g. "vxlan") and custom (e.g. "tunnel_header_0") tunnels
cannot be combined, but the match params interface does not have fields
for matching on vxlan gbp. To match vxlan bgp, the tc_tun layer uses
tunnel_header_0.

Allow matching on both VNI and GBP by matching the VNI with a custom
tunnel header instead of the symbolic field name.

Matching solely on the VNI continues to use the symbolic field name.

Fixes: 74a778b4 ("net/mlx5: HWS, added definers handling")
Signed-off-by: Vlad Dogaru <vdogaru@nvidia.com>
Reviewed-by: Yevgeny Kliteynik <kliteyn@nvidia.com>
Signed-off-by: Mark Bloch <mbloch@nvidia.com>
Reviewed-by: Michal Swiatkowski <michal.swiatkowski@linux.intel.com>
Link: https://patch.msgid.link/20250423083611.324567-2-mbloch@nvidia.com


Signed-off-by: Jakub Kicinski <kuba@kernel.org>