mb/siemens/mc_ehl2: Enable downshift for Marvell PHYs

Set downshift counter to 2 for all Marvell PHYs on this mainboard before
the PHY downshifts to the next highest speed.

Change-Id: I32b5f25a3e1e0f962dff3110143e236992ef8e7d
Signed-off-by: Mario Scheithauer <mario.scheithauer@siemens.com>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/69887
Reviewed-by: Arthur Heymans <arthur@aheymans.xyz>
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
diff --git a/src/mainboard/siemens/mc_ehl/variants/mc_ehl2/devicetree.cb b/src/mainboard/siemens/mc_ehl/variants/mc_ehl2/devicetree.cb
index 8090927..e1c2972 100644
--- a/src/mainboard/siemens/mc_ehl/variants/mc_ehl2/devicetree.cb
+++ b/src/mainboard/siemens/mc_ehl/variants/mc_ehl2/devicetree.cb
@@ -191,6 +191,7 @@
 				register "led_1_ctrl" = "1"
 				# INTn is routed to LED[2] pin
 				register "enable_int" = "true"
+				register "downshift_cnt" = "2"
 				device mdio 0 on    # PHY address
 					ops m88e1512_ops
 				end
@@ -206,6 +207,7 @@
 				register "led_1_ctrl" = "1"
 				# INTn is routed to LED[2] pin
 				register "enable_int" = "true"
+				register "downshift_cnt" = "2"
 				device mdio 1 on    # PHY address
 					ops m88e1512_ops
 				end
@@ -224,6 +226,7 @@
 				register "led_1_ctrl" = "1"
 				# INTn is routed to LED[2] pin
 				register "enable_int" = "true"
+				register "downshift_cnt" = "2"
 				device mdio 1 on    # PHY address
 					ops m88e1512_ops
 				end