doc/device-tree: Add OpenCAPI device tree bindings
doc/device-tree: Add OpenCAPI device tree bindings

Suggested-by: Stewart Smith <ec31ab75ddf977353c8f660f92ea8b23f64aef25@linux.vnet.ibm.com>
Signed-off-by: Andrew Donnellan <efc2d7c347a094a6ec1d918179e819039044c564@au1.ibm.com>
Signed-off-by: Stewart Smith <ec31ab75ddf977353c8f660f92ea8b23f64aef25@linux.vnet.ibm.com>

shenki/skiboot,stewart-ibm/skiboot,shenki/skiboot,shenki/skiboot,qemu/skiboot,shenki/skiboot,open-power/skiboot,shenki/skiboot,open-power/skiboot,qemu/skiboot,stewart-ibm/skiboot,open-power/skiboot,stewart-ibm/skiboot,legoater/skiboot,qemu/skiboot,open-power/skiboot,legoater/skiboot,qemu/skiboot,open-power/skiboot,legoater/skiboot,qemu/skiboot,legoater/skiboot,legoater/skiboot