net/mlx5e: Fix error handling in mlx5e_refresh_tirs

Allocation failure is outside the critical lock section and should
return immediately rather than jumping to the unlock section.

Also unlock as soon as required and remove the now redundant jump label.

Fixes: 80a2a902 ("net/mlx5e: Add a lock on tir list")
Signed-off-by: Saeed Mahameed <saeedm@nvidia.com>