Follow the advise of Russell King allows to greatly improve the driver
for RealTek's 1G and 2.5G Ethernet PHYs. The results are full/half
duplex as well as Gbit master/slave property being read from PHY
Specific Status Register (PHYSR), and fixes regarding link-partner
advertisement.
Fixes: #14504
Signed-off-by: Daniel Golle <daniel@makrotopia.org>
