net/mlx5: Fix memory leak in error flow of port set buffer

In the cited commit, shared buffer updates were added whenever
port buffer gets updated.

However, in case the shared buffer update fails, exiting early from
port_set_buffer() is performed without freeing previously-allocated memory.

Fix it by jumping to out label where memory is freed before returning
with error.

Fixes: a440030d ("net/mlx5e: Update shared buffer along with device buffer changes")
Signed-off-by: Maher Sanalla <msanalla@nvidia.com>
Reviewed-by: Moshe Shemesh <moshe@nvidia.com>
Signed-off-by: Saeed Mahameed <saeedm@nvidia.com>