dt-bindings: arm: syna: remove unstable remark

Marvell Berlin SoCs (later Syna) bindings were marked as
work-in-progress / unstable in 2015 in commit f07b4e4 ("Documentation:
bindings: berlin: consider our dt bindings as unstable").  Almost nine
years is enough, so drop the "unstable" remark and expect usual ABI
rules.

Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Link: https://lore.kernel.org/r/20240224084414.6264-1-krzysztof.kozlowski@linaro.org
Signed-off-by: Rob Herring <robh@kernel.org>

Author: krzk

Documentation/devicetree/bindings/arm/syna.txt

@@ -6,18 +6,6 @@ berlin SoCs are now Synaptics' SoCs now.
 
 ---------------------------------------------------------------
 
-Work in progress statement:
-
-Device tree files and bindings applying to Marvell Berlin SoCs and boards are
-considered "unstable". Any Marvell Berlin device tree binding may change at any
-time. Be sure to use a device tree binary and a kernel image generated from the
-same source tree.
-
-Please refer to Documentation/devicetree/bindings/ABI.rst for a definition of a
-stable binding/ABI.
-
----------------------------------------------------------------
-
 Boards with a SoC of the Marvell Berlin family, e.g. Armada 1500
 shall have the following properties: