arm64: dts: marvell: 98dx25xx: use correct property for i2c gpios

Use the correct names for scl-gpios and sda-gpios so that the generic
i2c recovery code will find them. While we're here set the
GPIO_OPEN_DRAIN flag on the gpios.

Fixes: b795fadf ("arm64: dts: marvell: Add Armada 98DX2530 SoC and RD-AC5X board")
Signed-off-by: Chris Packham <chris.packham@alliedtelesis.co.nz>
Signed-off-by: Gregory CLEMENT <gregory.clement@bootlin.com>