ARM: dts: renesas: Add compatible properties to KSZ9031 Ethernet PHYs on Salvator...

ARM: dts: renesas: Add compatible properties to KSZ9031 Ethernet PHYs on Salvator-X boards

Add compatible values to Ethernet PHY subnodes representing Micrel
KSZ9031 PHYs on R-Car Gen3 Salvator-X boards. This allows software
to identify the PHY model at any time, regardless of the state of
the PHY reset line.

This is a fix for missed addition of these properties on Salvator-X
boards.

Ported from Linux kernel commit 722d55f3a9bd810f3a1a31916cc74e2915a994ce .

Signed-off-by: Marek Vasut <marek.vasut+renesas@mailbox.org>