net/mlx5e: TC, Remove redundant WARN_ON()

The case where the packet is not offloaded and needs to be restored
to slow path and couldn't find expected tunnel information should not
dump a call trace to the user. there is a debug call.

Signed-off-by: Roi Dayan <roid@nvidia.com>
Reviewed-by: Maor Dickman <maord@nvidia.com>
Signed-off-by: Saeed Mahameed <saeedm@nvidia.com>