* use interface mode switching only when operating in C45 mode
Linux prevents switching the interface mode when using C22 MDIO,
hence use rate-adapter mode in case the PHY controlled via C22.
* use phy_read_paged where appropriate
* use existing generic inline functions to handle 10GbE advertisements
instead of redundantly defining register macros in realtek.c which
are not actually vendor-specific.
* make sure 10GbE advertisement is valid, preventing false-positive
warning "Downshift occurred from negotiated speed 2.5Gbps to actual
speed 1Gbps, check cabling!" with some link-partners using 1G mode.
* Support Link Down Power Saving Mode (ALDPS)
Signed-off-by: Daniel Golle <daniel@makrotopia.org>