ARM: dts: imx6qp-prtwd3: update RGMII delays for sja1105 switch

In the new behavior, the sja1105 driver expects there to be explicit
RGMII delays present on the fixed-link ports, otherwise it will complain
that it falls back to legacy behavior, which is to apply RGMII delays
incorrectly derived from the phy-mode string.

In this case, the legacy behavior of the driver is to apply both RX and
TX delays. To preserve that, add explicit 2 nanosecond delays, which are
identical with what the driver used to add (a 90 degree phase shift).
The delays from the phy-mode are ignored by new kernels (it's still
RGMII as long as it's "rgmii*" something), and the explicit
{rx,tx}-internal-delay-ps properties are ignored by old kernels, so the
change works both ways.

Signed-off-by: Vladimir Oltean <[e-mail]>
Reviewed-by: Florian Fainelli <[e-mail]>
Reviewed-by: Oleksij Rempel <[e-mail]>
Signed-off-by: Shawn Guo <[e-mail]>

arch/arm/boot/dts/imx6qp-prtwd3.dts

···
 				label = "cpu";
 				ethernet = <&fec>;
 				phy-mode = "rgmii-id";
+				rx-internal-delay-ps = <2000>;
+				tx-internal-delay-ps = <2000>;
 
 				fixed-link {
 					speed = <100>;