net/mlx5: DR, Expose steering rule functionality

Rules are the actual objects that tie matchers, header values and
actions. Each rule belongs to a matcher, which can hold multiple rules
sharing the same mask. Each rule is a specific set of values and
actions.
When a packet reaches a matcher it is being matched against the
matcher`s rules. In case of a match over a rule its actions will be
executed. Each rule object contains a set of STEs, where each STE is a
definition of match values and actions defined by the rule.
This file handles the rule operations and processing.

Signed-off-by: Alex Vesker <valex@mellanox.com>
Signed-off-by: Erez Shitrit <erezsh@mellanox.com>
Reviewed-by: Mark Bloch <markb@mellanox.com>
Signed-off-by: Saeed Mahameed <saeedm@mellanox.com>