ARM: dts: exynos: Add minimal clkout parameters to Exynos3250 PMU

Add minimal parameters needed by the Exynos CLKOUT driver to Exynos3250
PMU node. This fixes the following warning on boot:

exynos_clkout_init: failed to register clkout clock

Fixes: d19bb397 ("ARM: dts: exynos: Update PMU node with CLKOUT related data")
Cc: <stable@vger.kernel.org>
Signed-off-by: Marek Szyprowski <m.szyprowski@samsung.com>
Signed-off-by: Krzysztof Kozlowski <krzk@kernel.org>