mlxsw: reg: Add support for VLAN RIF as part of RITR register

Router interfaces (RIFs) constructed on top of VLAN-aware bridges are of
"VLAN" type, whereas RIFs constructed on top of VLAN-unaware bridges of
"FID" type.

In other words, the RIF type is derived from the underlying FID type.
VLAN RIFs are used on top of 802.1Q FIDs, whereas FID RIFs are used on
top of 802.1D FIDs.

Currently 802.1Q FIDs are emulated using 802.1D FIDs, and therefore VLAN
RIFs are emulated using FID RIFs.

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

Add the relevant fields to RITR register, add pack() function for VLAN
RIF and rename one field to fit the internal name.

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