mlxsw: spectrum: Rename MLXSW_SP_RIF_TYPE_VLAN

Currently, the driver emulates 802.1Q FIDs using 802.1D FIDs. As such,
the RIFs configured on top of these FIDs are FID RIFs and not VLAN RIFs.

As part of converting the driver to the unified bridge model, 802.1Q
FIDs and VLAN RIFs will be used.

As a preparation for this change, rename the emulated VLAN RIFs from
'MLXSW_SP_RIF_TYPE_VLAN' to 'MLXSW_SP_RIF_TYPE_VLAN_EMU'. After the
conversion the emulated VLAN RIFs will be removed.

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>