The MACCHIATOBin board has a PCA9548 I2C mux for the SFP ports on
CP100 master I2C bus 1.  Add the DT description for it.
Signed-off-by: NRussell King <rmk+kernel@armlinux.org.uk>
Signed-off-by: NGregory CLEMENT <gregory.clement@free-electrons.com>