mlxsw: spectrum_switchdev: Do not treat static FDB entries as sticky

The driver currently treats static FDB entries as both static and
sticky. This is incorrect and prevents such entries from being roamed to
a different port via learning.

Fix this by configuring static entries with ageing disabled and roaming
enabled.

In net-next we can add proper support for the newly introduced 'sticky'
flag.

Fixes: 56ade8fe ("mlxsw: spectrum: Add initial support for Spectrum ASIC")
Signed-off-by: Ido Schimmel <idosch@mellanox.com>
Reported-by: Alexander Petrovskiy <alexpe@mellanox.com>
Reviewed-by: Petr Machata <petrm@mellanox.com>
Signed-off-by: David S. Miller <davem@davemloft.net>