net/mlx5e: Fix error flow in change profile

Move priv memset from init to cleanup to avoid double priv cleanup
that can happen on profile change if also roolback fails.
Add missing cleanup flow in mlx5e_netdev_attach_profile().

Fixes: c4d7eb57 ("net/mxl5e: Add change profile method")
Signed-off-by: Roi Dayan <roid@nvidia.com>
Signed-off-by: Saeed Mahameed <saeedm@nvidia.com>