net/mlx5: Refactor mlx5_get_flow_namespace

[ Upstream commit 4588fed7 ]

Have all the namespace type check in the same switch case.

Signed-off-by: Maor Gottlieb <maorg@nvidia.com>
Reviewed-by: Mark Bloch <mbloch@nvidia.com>
Signed-off-by: Saeed Mahameed <saeedm@nvidia.com>
Reviewed-by: Leon Romanovsky <leonro@nvidia.com>
Signed-off-by: Saeed Mahameed <saeedm@nvidia.com>
Stable-dep-of: c08d3e62 ("net/mlx5: Fix RDMA TX steering prio")
Signed-off-by: Sasha Levin <sashal@kernel.org>