net/mlx5: fix GRE protocol type translation

net/mlx5: fix GRE protocol type translation

When application creates several flows to match on GRE tunnel
without explicitly specifying GRE protocol type value in
flow rules, PMD will translate that to zero mask.
RDMA-CORE cannot distinguish between different inner flow types and
produces identical matchers for each zero mask.

The patch extracts inner header type from flow rule and forces it
in GRE protocol type, if application did not specify
any without explicitly specifying GRE protocol type value in
flow rules, protocol type value.

Fixes: fc2c498ccb94 ("net/mlx5: add Direct Verbs translate items")
Cc: stable@dpdk.org
Signed-off-by: Gregory Etelson <getelson@nvidia.com>
Acked-by: Viacheslav Ovsiienko <viacheslavo@nvidia.com>