net/mlx5: HWS, removed wrong access to a number of rules variable

Removed wrong access to the num_of_rules field of the matcher.
This is a usual u32 variable, but the access was as if it was atomic.

This fixes the following CI warnings:
  mlx5hws_bwc.c:708:17: warning: large atomic operation may incur significant performance penalty;
  the access size (4 bytes) exceeds the max lock-free size (0 bytes) [-Watomic-alignment]

Fixes: 510f9f61 ("net/mlx5: HWS, added API and enabled HWS support")
Reported-by: kernel test robot <lkp@intel.com>
Closes: https://lore.kernel.org/oe-kbuild-all/202409291101.6NdtMFVC-lkp@intel.com/


Signed-off-by: Yevgeny Kliteynik <kliteyn@nvidia.com>
Reviewed-by: Itamar Gozlan <igozlan@nvidia.com>
Signed-off-by: Tariq Toukan <tariqt@nvidia.com>
Signed-off-by: Paolo Abeni <pabeni@redhat.com>