mlxsw: Revert "Prepare for XM implementation - LPM trees"

This reverts commit 923ba95e ("Merge branch
'mlxsw-spectrum-prepare-for-xm-implementation-lpm-trees'").

Signed-off-by: Petr Machata <petrm@nvidia.com>
Signed-off-by: Ido Schimmel <idosch@nvidia.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>