arm64: dts: zii-ultra: fix i2c pin configuration

Reduce slew rate and set drive strength to 105 Ohm. The previous settings
had some issues with signal ringing, due to the slew rate being too fast.

Signed-off-by: Lucas Stach <l.stach@pengutronix.de>
Signed-off-by: Shawn Guo <shawnguo@kernel.org>