ARM: dts: imx6sx-softing-vining-2000: Fix the 'interrupt-parent' property

The correct property name is 'interrupt-parent', so fix it accordingly.

This fixes the following build warning:

arch/arm/boot/dts/imx6sx-softing-vining-2000.dtb: Warning (interrupts_property): interrupts size is (8), expected multiple of 12 in /soc/aips-bus@02100000/ethernet@02188000/mdio/ethernet0-phy@0
arch/arm/boot/dts/imx6sx-softing-vining-2000.dtb: Warning (interrupts_property): interrupts size is (8), expected multiple of 12 in /soc/aips-bus@02100000/ethernet@021b4000/mdio/ethernet1-phy@0

Cc: Christoph Fritz <chf.fritz@googlemail.com>
Signed-off-by: Fabio Estevam <fabio.estevam@nxp.com>
Signed-off-by: Shawn Guo <shawnguo@kernel.org>