mlx4_core: Deprecate log_num_vlan module param

Enable the maximum size (128) supported by the device for the shadow
vlans table, ignoring the module parameter that overrides it.  This
table is only used by the IBoE control plane for setting a vlan index
into an RC/UC QP context or UD Address Handle.

Signed-off-by: Or Gerlitz <ogerlitz@mellanox.com>
Signed-off-by: Roland Dreier <roland@purestorage.com>