net/mlx5: DR, No need for atomic refcount for internal SW steering resources

No need for an atomic refcounter for the STE and hashtables.
These are internal SW steering resources and they are always
under domain mutex.

This also fixes the following refcount error:
  refcount_t: addition on 0; use-after-free.
  WARNING: CPU: 9 PID: 3527 at lib/refcount.c:25 refcount_warn_saturate+0x81/0xe0
  Call Trace:
   dr_table_init_nic+0x10d/0x110 [mlx5_core]
   mlx5dr_table_create+0xb4/0x230 [mlx5_core]
   mlx5_cmd_dr_create_flow_table+0x39/0x120 [mlx5_core]
   __mlx5_create_flow_table+0x221/0x5f0 [mlx5_core]
   esw_create_offloads_fdb_tables+0x180/0x5a0 [mlx5_core]
   ...

Fixes: 26d688e3

 ("net/mlx5: DR, Add Steering entry (STE) utilities")
Signed-off-by: Yevgeny Kliteynik <kliteyn@mellanox.com>
Reviewed-by: Alex Vesker <valex@mellanox.com>
Signed-off-by: Saeed Mahameed <saeedm@mellanox.com>