mlxsw: spectrum_switchdev: Add an internal API for VXLAN leave

mlxsw: spectrum_switchdev: Add an internal API for VXLAN leave

There is asymmetry in how the VXLAN join and leave functions are used.
The join function (mlxsw_sp_bridge_vxlan_join()) is only called in
response to netdev events (e.g., VXLAN device joining a bridge), but the
leave function is also called in response to switchdev events (e.g.,
VLAN configuration on top of the VXLAN device) in order to invalidate
VNI to FID mappings.

This asymmetry will cause problems when the functions will be later
extended to mark VXLAN bridge ports as offloaded or not.

Therefore, create an internal function (__mlxsw_sp_bridge_vxlan_leave())
that is used to invalidate VNI to FID mappings and call it from
mlxsw_sp_bridge_vxlan_leave() which will only be invoked in response to
netdev events, like mlxsw_sp_bridge_vxlan_join().

No functional changes intended.

Signed-off-by: Amit Cohen <amcohen@nvidia.com>
Reviewed-by: Petr Machata <petrm@nvidia.com>
Reviewed-by: Ido Schimmel <idosch@nvidia.com>
Signed-off-by: Petr Machata <petrm@nvidia.com>
Reviewed-by: Simon Horman <horms@kernel.org>
Link: https://patch.msgid.link/f3a32bd2d87a0b7ac4d2bb98a427dc6d95a01cd0.1742224300.git.petrm@nvidia.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>