net: phy: smsc: export functions for use by meson-gxl PHY driver

The Amlogic Meson internal PHY's have the same register layout as
certain SMSC PHY's (also for non-c22-standard registers). This seems
to be more than just coincidence. Apparently they also need the same
workaround for EDPD mode (energy detect power down). Therefore let's
export SMSC PHY driver functionality for use by the meson-gxl PHY
driver.

Signed-off-by: Heiner Kallweit <hkallweit1@gmail.com>
Signed-off-by: Chris Healy <healych@amazon.com>
Signed-off-by: David S. Miller <davem@davemloft.net>