arm64: dts: ti: k3-j7200-common-proc-board: Configure the SERDES lane function

First two lanes of SERDES is connected to PCIe, third lane is
connected to QSGMII and the last lane is connected to USB. However,
Cadence torrent SERDES doesn't support more than 2 protocols
at the same time. Configure it only for PCIe and QSGMII.

Signed-off-by: Kishon Vijay Abraham I <kishon@ti.com>
Signed-off-by: Roger Quadros <rogerq@ti.com>
Signed-off-by: Nishanth Menon <nm@ti.com>
Reviewed-by: Vignesh Raghavendra <vigneshr@ti.com>
Link: https://lore.kernel.org/r/20200930122032.23481-6-rogerq@ti.com

arch/arm64/boot/dts/ti/k3-j7200-common-proc-board.dts

@@ -7,6 +7,7 @@
 
 #include "k3-j7200-som-p0.dtsi"
 #include <dt-bindings/net/ti-dp83867.h>
+#include <dt-bindings/mux/ti-serdes.h>
 
 / {
 	chosen {
@@ -185,3 +186,8 @@
 	ti,driver-strength-ohm = <50>;
 	disable-wp;
 };
+
+&serdes_ln_ctrl {
+	idle-states = <J7200_SERDES0_LANE0_PCIE1_LANE0>, <J7200_SERDES0_LANE1_PCIE1_LANE1>,
+		      <J7200_SERDES0_LANE2_QSGMII_LANE1>, <J7200_SERDES0_LANE3_IP4_UNUSED>;
+};