dts: bindings: provide generic yaml description for i2c-devices

Provide generic yaml description for i2c-devices such as sensors

New yaml binding category 'parent/child' is added.
It aims at binding two types of related node such as bus master and
bus slave.
In case of i2c-device object, parent property is 'bus' with value 'i2c'.
In the mean time, i2c node gets child property bus. Master and slave bus
values should match.
As such, 'i2c' node is bus master and 'i2c-devices' nodes are bus slaves

Signed-off-by: Erwan Gouriou <erwan.gouriou@linaro.org>
3 files changed