ARM: dts: opos6ul: add ksz8081 phy properties

Commit c7e73b50 ("ARM: imx: mach-imx6ul: remove 14x14 EVK specific
PHY fixup") removed a PHY fixup that setted the clock mode and the LED
mode.
Make the Ethernet interface work again by doing as advised in the
commit's log, set clock mode and the LED mode in the device tree.

Fixes: c7e73b50 ("ARM: imx: mach-imx6ul: remove 14x14 EVK specific PHY fixup")
Signed-off-by: Sébastien Szymanski <sebastien.szymanski@armadeus.com>
Reviewed-by: Oleksij Rempel <o.rempel@pengutronix.de>
Signed-off-by: Shawn Guo <shawnguo@kernel.org>