ARM: dts: r8a7790: lager: use demuxer for IIC0/I2C0

Make it possible to select which I2C IP core you want to run on the
EXIO-A connector. This is the reference how to use this feature. Update
the copyright while we are here.

Signed-off-by: Wolfram Sang <wsa+renesas@sang-engineering.com>
Signed-off-by: Simon Horman <horms+renesas@verge.net.au>