net/mlx5: support matching GRE optional fields

net/mlx5: support matching GRE optional fields

This patch adds matching on the optional fields (checksum/key/sequence)
of GRE header. The matching on checksum and sequence fields requests
support from rdma-core with the capability of misc5 and tunnel_header 0-3.

For patterns without checksum and sequence specified, keep using misc for
matching as before, but for patterns with checksum or sequence, validate
capability first and then use misc5 for the matching.

Signed-off-by: Sean Zhang <xiazhang@nvidia.com>
Acked-by: Viacheslav Ovsiienko <viacheslavo@nvidia.com>