net: phy: marvell: add SFP support for 88E1510

Add support for SFP cages connected to the Marvell 88E1512 transceiver.
88E1512 supports for SGMII/1000Base-X/100Base-FX media type with RGMII
on system interface. Configure PHY to appropriate mode depending on the
type of SFP inserted. On SFP removal configure PHY to the RGMII-copper
mode so RJ-45 port can still work.

Signed-off-by: Ivan Bornyakov <i.bornyakov@metrotek.ru>
Link: https://lore.kernel.org/r/20210812134256.2436-1-i.bornyakov@metrotek.ru


Signed-off-by: Jakub Kicinski <kuba@kernel.org>