mlxsw: spectrum_fid: Update FID structure prior to device configuration

Currently, the only FID attributes that are edited after FID creation
are its VNI and NVE tunnel flood pointer. This is achieved by eventually
invoking mlxsw_sp_fid_vni_op() with an updated set of arguments.

In the future, more FID attributes will need to be edited, such as the
ingress RIF configured on top of the FID.

Therefore, it makes sense to encapsulate all the FID edit logic in one
function that will perform the edit based on an updated FID structure.

To that end, update the FID structure before invoking the various edit
operations that eventually call into mlxsw_sp_fid_vni_op(). Use the
updated structure as the sole argument of the edit operations.

Signed-off-by: Amit Cohen <amcohen@nvidia.com>
Signed-off-by: Ido Schimmel <idosch@nvidia.com>
Signed-off-by: David S. Miller <davem@davemloft.net>