net/mlx5: fix 32bit build

We can't use the division operator on 64 bits integers, that breaks
32 bits build. Instead use the relevant helper.

Fixes: 6ddac26c ("net/mlx5e: Add support to modify hardware flow meter parameters")
Acked-by: Saeed Mahameed <saeedm@nvidia.com>
Link: https://lore.kernel.org/r/ecb00ddd1197b4f8a4882090206bd2eee1eb8b5b.1657005206.git.pabeni@redhat.com


Signed-off-by: Paolo Abeni <pabeni@redhat.com>