arm64: dts: renesas: salvator-common: adv748x: Override secondary addresses

Ensure that the ADV748x device addresses do not conflict, and group them
together (visually in i2cdetect)

Signed-off-by: Kieran Bingham <kieran.bingham@ideasonboard.com>
Signed-off-by: Simon Horman <horms+renesas@verge.net.au>