mlxsw: Rename mlxsw_reg_mtptptp_pack() to mlxsw_reg_mtptpt_pack()

The right name of the register is MTPTPT, which refers to Monitoring
Precision Time Protocol Trap Register.

Therefore, rename the function mlxsw_reg_mtptptp_pack() to
mlxsw_reg_mtptpt_pack().

Signed-off-by: Danielle Ratson <danieller@nvidia.com>
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>