dt-bindings: arm: samsung: Drop syscon compatible from CHIPID binding

The "syscon" compatible string was introduced mainly to allow sharing
of the CHIPID IO region between multiple drivers. However, such sharing
can be also done without an additional compatible so remove "syscon".

Suggested-by: Krzysztof Kozlowski <krzk@kernel.org>
Signed-off-by: Sylwester Nawrocki <s.nawrocki@samsung.com>
Reviewed-by: Krzysztof Kozlowski <krzk@kernel.org>
Signed-off-by: Rob Herring <robh@kernel.org>