net: phy: marvell: add downshift support for M88E1240

Add downshift support for 88E1240, it uses the same downshift
configuration registers as 88E1011.
Signed-off-by: Maxim Kochetkov <fido_max@inbox.ru>
Link: https://lore.kernel.org/r/20210428095356.621536-1-fido_max@inbox.ruSigned-off-by: Jakub Kicinski <kuba@kernel.org>

drivers/net/phy/marvell.c

@@ -2870,6 +2870,8 @@ static struct phy_driver marvell_drivers[] = {
 		.get_sset_count = marvell_get_sset_count,
 		.get_strings = marvell_get_strings,
 		.get_stats = marvell_get_stats,
+		.get_tunable = m88e1011_get_tunable,
+		.set_tunable = m88e1011_set_tunable,
 	},
 	{
 		.phy_id = MARVELL_PHY_ID_88E1116R,