sfc: Remove PTP code for Siena

rx_tx_inline is now always true.
The special event list is no longer needed, event handling is always
inline.
Event MCDI_EVENT_CODE_PTP_RX is no longer needed.

Signed-off-by: Martin Habets <habetsm.xilinx@gmail.com>
Acked-by: Edward Cree <ecree.xilinx@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>