net: stmmac: fix ptp timestamping on Rx on gmac4

The current driver only enables Pdelay_Req and Pdelay_Resp when
HWTSTAMP_FILTER_PTP_V2_EVENT, HWTSTAMP_FILTER_PTP_V1_L4_EVENT or
HWTSTAMP_FILTER_PTP_V2_L4_EVENT is requested. This results in ptp sync on
slave mode to report 'received SYNC without timestamp' when using ptp4l.

Although the hardware can support Sync, Pdelay_Req and Pdelay_resp by
setting bit14 annd bits 17/16 to 01 this leaves Delay_Req timestamps out.

Fix this by enabling all event and general messages timestamps.
This includes SYNC, Follow_Up, Delay_Req, Delay_Resp, Pdelay_Req,
Pdelay_Resp and Pdelay_Resp_Follow_Up messages.

Signed-off-by: Ilias Apalodimas <ilias.apalodimas@linaro.org>
Acked-by: Jose Abreu <joabreu@synopsys.com>
Tested-by: Alexandre TORGUE <alexandre.torgue@st.com>
Signed-off-by: David S. Miller <davem@davemloft.net>