dt-bindings: trivial-devices: Document CPLD on DH electronics boards

The CPLD on DH electronics boards is used to model arbitrary custom
glue logic, however it does have SPI interface. Document the CPLD DT
binding as trivial SPI device.
Signed-off-by: Marek Vasut <marex@denx.de>
Cc: Fabio Estevam <festevam@gmail.com>
Cc: Mark Brown <broonie@kernel.org>
Cc: Peng Fan <peng.fan@nxp.com>
Cc: Rob Herring <robh+dt@kernel.org>
Cc: Shawn Guo <shawnguo@kernel.org>
Cc: devicetree@vger.kernel.org
Cc: NXP Linux Team <linux-imx@nxp.com>
To: linux-spi@vger.kernel.org
Signed-off-by: Rob Herring <robh@kernel.org>
Link: https://lore.kernel.org/r/20220407210106.256027-1-marex@denx.de

Documentation/devicetree/bindings/trivial-devices.yaml

@@ -87,6 +87,8 @@ properties:
           - devantech,srf08
             # Devantech SRF10 ultrasonic ranger
           - devantech,srf10
+            # DH electronics GmbH on-board CPLD trivial SPI device
+          - dh,dhcom-board
             # DA9053: flexible system level PMIC with multicore support
           - dlg,da9053
             # DA9063: system PMIC for quad-core application processors