mlxsw: reg: Add Policy-Engine Port Range Register

Add the Policy-Engine Port Range Register that is used for configuring
port range identification.

Signed-off-by: Ido Schimmel <idosch@nvidia.com>
Reviewed-by: Petr Machata <petrm@nvidia.com>
Signed-off-by: Petr Machata <petrm@nvidia.com>
Link: https://lore.kernel.org/r/d1a1f53d758f7452cf5abfe006b23496076ec3e6.1689092769.git.petrm@nvidia.com


Signed-off-by: Jakub Kicinski <kuba@kernel.org>