dt-bindings: Document Phytec phyCORE-RK3288 RDK

Add documentation for the PCM-947 carrier board, a RK3288 based
development board made by PHYTEC.

Signed-off-by: Wadim Egorov <w.egorov@phytec.de>
Signed-off-by: Heiko Stuebner <heiko@sntech.de>
1 file changed