net/mlx5e: Add intermediate struct for TC flow parsing attributes

Add intermediate structure to store attributes parsed from TC filter
matching/actions parts which are soon to be configured into the HW.

Currently put there the flow matching spec after being parsed. More
content to be added in down-stream patch.

This patch doesn't change any functionality.

Signed-off-by: Or Gerlitz <ogerlitz@mellanox.com>
Signed-off-by: Saeed Mahameed <saeedm@mellanox.com>