net: dsa: sja1105: always enable the send_meta options

incl_srcpt has the limitation, mentioned in commit b4638af8 ("net:
dsa: sja1105: always enable the INCL_SRCPT option"), that frames with a
MAC DA of 01:80:c2:xx:yy:zz will be received as 01:80:c2:00:00:zz unless
PTP RX timestamping is enabled.

The incl_srcpt option was initially unconditionally enabled, then that
changed with commit 42824463 ("net: dsa: sja1105: Limit use of
incl_srcpt to bridge+vlan mode"), then again with b4638af8 ("net:
dsa: sja1105: always enable the INCL_SRCPT option"). Bottom line is that
it now needs to be always enabled, otherwise the driver does not have a
reliable source of information regarding source_port and switch_id for
link-local traffic (tag_8021q VLANs may be imprecise since now they
identify an entire bridging domain when ports are not standalone).

If we accept that PTP RX timestamping (and therefore, meta frame
generation) is always enabled in hardware, then that limitation could be
avoided and packet...