Documentation: of: Document the bindings used by Juno R1 PCIe host bridge

ARM's Juno R1 board used PLDA XpressRICH3-AXI IP to implement a PCIe host
bridge. Introduce "plda" as vendor prefix for PLDA and document the DT
bindings for PLDA XpressRICH3-AXI IP as well as ARM's Juno R1.

Signed-off-by: Liviu Dudau <Liviu.Dudau@arm.com>
Acked-by: Mark Rutland <mark.rutland@arm.com>
diff --git a/Documentation/devicetree/bindings/vendor-prefixes.txt b/Documentation/devicetree/bindings/vendor-prefixes.txt
index 82d2ac9..57653eb 100644
--- a/Documentation/devicetree/bindings/vendor-prefixes.txt
+++ b/Documentation/devicetree/bindings/vendor-prefixes.txt
@@ -168,6 +168,7 @@
 phytec	PHYTEC Messtechnik GmbH
 picochip	Picochip Ltd
 plathome	Plat'Home Co., Ltd.
+plda	PLDA
 pixcir  PIXCIR MICROELECTRONICS Co., Ltd
 powervr	PowerVR (deprecated, use img)
 qca	Qualcomm Atheros, Inc.