ARM: dts: Add pinmuxing for i2c2 and i2c3 for LogicPD SOM-LV

Since I2C1 and I2C4 have explicit pinmuxing set, let's be on the
safe side and set the pin muxing for I2C2 and I2C3.

Signed-off-by: Adam Ford <aford173@gmail.com>
Signed-off-by: Tony Lindgren <tony@atomide.com>