mlxsw: spectrum: Set KVH XLT cache mode for Spectrum2/3

Set a profile option to instruct FW to use 1/2 of KVH for XLT cache, not
the whole one.

Signed-off-by: Jiri Pirko <jiri@nvidia.com>
Signed-off-by: Ido Schimmel <idosch@nvidia.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>