mlxsw: spectrum: Clear PTP configuration after unregistering the netdevice

Currently as part of removing port, PTP API is called to clear the
existing configuration and set the 'rx_filter' and 'tx_type' to zero.
The clearing is done before unregistering the netdevice, which means that
there is a window of time in which the user can reconfigure PTP in the
port, and this configuration will not be cleared.

Reorder the operations, clear PTP configuration after unregistering the
netdevice.

Fixes: 87486427 ("mlxsw: spectrum: PTP: Support SIOCGHWTSTAMP, SIOCSHWTSTAMP ioctls")
Signed-off-by: Amit Cohen <amcohen@nvidia.com>
Signed-off-by: Ido Schimmel <idosch@nvidia.com>
Signed-off-by: Petr Machata <petrm@nvidia.com>
Signed-off-by: David S. Miller <davem@davemloft.net>