Introduce DP83867 PHY driver

[kd]

Summary

DP83867 is a 10/100/1000 Texas Instruments PHY.
Only SGMII mode is supported.
Link status changes can be checked through an interrupt generated by the PHY if available

[bsd_dino.sk]

I'd like to test this review, but two errors occured when building. First one, unknown function 'device_get_property' means I need fresh sources (I see it in recently fetched git repository).
Second one, no member named 'mii_maxspeed' in 'struct mii_softc' I can't resolve recently - looking into file sys/dev/mii/miivar.h, where struct mii_softc is defined, does not show such member of structure.

[kd]

In D32813#745936, @bsd_dino.sk wrote:

I'd like to test this review, but two errors occured when building. First one, unknown function 'device_get_property' means I need fresh sources (I see it in recently fetched git repository).
Second one, no member named 'mii_maxspeed' in 'struct mii_softc' I can't resolve recently - looking into file sys/dev/mii/miivar.h, where struct mii_softc is defined, does not show such member of structure.

device_get_property code was merged into main a couple moths ago, so you need relatively fresh sources indeed.
The second error should dissapear after applying D32812 and D32727.

[bsd_dino.sk]

Looking a bit more into it, I think maxspeed variable and mii_maxspeed struct member is just read from DTB, but not used anywhere.

[kd]

In D32813#745944, @bsd_dino.sk wrote:

Looking a bit more into it, I think maxspeed variable and mii_maxspeed struct member is just read from DTB, but not used anywhere.

With D32727 applied it is used in mii_phy_dev_attach.

[bsd_dino.sk]

After some mail exchange regarding problem elsewhere, applied this review minus maxspeed handling for brevity, DP83867 PHY looks like working for me (I need to fix something else unrelated to this review to be sure) - at least media status sense and autonegotiation works as expected.