mlxsw: reg: Remove unused functions

The functions mlxsw_reg_sfd_uc_unpack() and
mlxsw_reg_sfd_uc_lag_unpack() are not used. Remove them.

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>