net/mlx5: E-Switch, Refactor eswitch egress acl codes

Refactor the egress acl codes so that offloads and legacy modes
can configure specifically their own needs of egress acl table,
groups and rules. While at it, restructure the eswitch egress
acl codes into eswitch directory and different files:
. Acl egress helper functions to acl_helper.c/h
. Acl egress functions used in offloads mode to acl_egress_ofld.c
. Acl egress functions used in legacy mode to acl_egress_lgy.c

This patch does not change any functionality.

Signed-off-by: Vu Pham <vuhuong@mellanox.com>
Signed-off-by: Saeed Mahameed <saeedm@mellanox.com>