net: dsa/mv88e6123_61_65: Add support for reading switch registers

The infrastructure can now report switch registers to ethtool.
Add support for it to the mv88e6123_61_65 driver.

Signed-off-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --cc drivers/net/dsa/mv88e6123_61_65.c
Simple merge

diff --cc drivers/net/dsa/mv88e6xxx.c
Simple merge

diff --cc drivers/net/dsa/mv88e6xxx.h
Simple merge