net/mlx5: Fix null-ptr-deref in mlx5_create_{inner_,}ttc_table()

Add NULL check for mlx5_get_flow_namespace() returns in
mlx5_create_inner_ttc_table() and mlx5_create_ttc_table() to prevent
NULL pointer dereference.

Fixes: 137f3d50 ("net/mlx5: Support matching on l4_type for ttc_table")
Signed-off-by: Henry Martin <bsdhenrymartin@gmail.com>
Reviewed-by: Mark Bloch <mbloch@nvidia.com>
Reviewed-by: Michal Swiatkowski <michal.swiatkowski@linux.intel.com>
Link: https://patch.msgid.link/20250418023814.71789-2-bsdhenrymartin@gmail.com


Signed-off-by: Jakub Kicinski <kuba@kernel.org>