net/mlx5e: Change flow flags type to unsigned long

To remove dependency on rtnl lock and allow concurrent modification of
'flags' field of tc flow structure, change flow flag type to unsigned long
and use atomic bit ops for reading and changing the flags. Implement
auxiliary functions for setting, resetting and getting specific flag, and
for checking most often used flag values.

Always set flags with smp_mb__before_atomic() to ensure that all
mlx5e_tc_flow are updated before concurrent readers can read new flags
value. Rearrange all code paths to actually set flow->rule[] pointers
before setting the OFFLOADED flag. On read side, use smp_mb__after_atomic()
when accessing flags to ensure that offload-related flow fields are only
read after the flags.

Signed-off-by: Vlad Buslov <vladbu@mellanox.com>
Reviewed-by: Jianbo Liu <jianbol@mellanox.com>
Reviewed-by: Roi Dayan <roid@mellanox.com>
Signed-off-by: Saeed Mahameed <saeedm@mellanox.com>