amd-xgbe-phy: Use the phy_driver flags field

Remove the setting of the transceiver type when retrieving the device
settings using ethtool and instead set the transceiver type in the
phy_driver structure flags field. Change the transceiver type to be
internal, also.

Signed-off-by: Tom Lendacky <thomas.lendacky@amd.com>
Signed-off-by: David S. Miller <davem@davemloft.net>