ARM: dts: exynos: Correct audio subsystem parent clock on Peach Chromebooks

The proper parent clock for audio subsystem for Exynos5420 and Exynos5800
SoCs is CLK_MAU_EPLL. This fixes following warning:

    clk: failed to reparent mout_audss to fout_epll: -22

Fixes: ed7d1307: ARM: dts: exynos: Enable HDMI audio support on Peach Pit
Fixes: bae0f445: ARM: dts: exynos: Enable HDMI audio support on Peach Pi
Signed-off-by: Marek Szyprowski <m.szyprowski@samsung.com>
Signed-off-by: Krzysztof Kozlowski <krzk@kernel.org>