ARM: dts: exynos: Split phandle in dmas property

Change representation of phandle array as then dt-schema counts number
of its items properly.

Signed-off-by: Maciej Falkowski <m.falkowski@samsung.com>
Signed-off-by: Marek Szyprowski <m.szyprowski@samsung.com>
Signed-off-by: Krzysztof Kozlowski <krzk@kernel.org>