net/mlx5: fix comparison sign in flow engine

net/mlx5: fix comparison sign in flow engine

The clang compiler warns on size mismatches of several
comparisons.

warning: comparison of integers of different signs

To resolve those the right types is used/cast to.

Fixes: 3e8edd0ef848 ("net/mlx5: update metadata register ID query")
Fixes: e554b672aa05 ("net/mlx5: support flow tag")
Fixes: c8f0abe7f89d ("net/mlx5: fix meter color register consideration")
Cc: stable@dpdk.org
Signed-off-by: Tal Shnaiderman <talshn@nvidia.com>
Acked-by: Matan Azrad <matan@nvidia.com>