dt-bindings: Add compatibles for undocumented trivial syscons

'intel,lgm-syscon', 'marvell,armada-3700-usb2-host-misc',
'mediatek,mt8135-pctl-a-syscfg', and 'mediatek,mt8135-pctl-b-syscfg' are
all used in DT binding examples and/or dts files, but are not
documented. Add them to syscon.yaml as they are all trivial cases.
Signed-off-by: Rob Herring <robh@kernel.org>
Reviewed-by: Matthias Brugger <matthias.bgg@gmail.com>
Signed-off-by: Lee Jones <lee.jones@linaro.org>
Link: https://lore.kernel.org/r/20220228221537.1700071-1-robh@kernel.org

Documentation/devicetree/bindings/mfd/syscon.yaml

@@ -44,6 +44,10 @@ properties:
               - hisilicon,hi6220-sramctrl
               - hisilicon,pcie-sas-subctrl
               - hisilicon,peri-subctrl
+              - intel,lgm-syscon
+              - marvell,armada-3700-usb2-host-misc
+              - mediatek,mt8135-pctl-a-syscfg
+              - mediatek,mt8135-pctl-b-syscfg
               - microchip,sparx5-cpu-syscon
               - mstar,msc313-pmsleep
               - rockchip,px30-qos