Introduce DP83822 PHY driver

DP83822 is a 10/100 Texas Instruments PHY.
Link status change interrupts are supported by the driver,
however not all boards have the PHY interrupt wired.
Because of that if failure to allocate an IRQ is not treated as an error.

Obtained from: Semihalf
Sponsored by: Alstom Group
Differential revision: https://reviews.freebsd.org/D32815