ARM: dts: Update the parent for Audss clocks in Exynos5420

Currently CLK_FOUT_EPLL was set as one of the parents of AUDSS mux.
As per the user manual, it should be CLK_MAU_EPLL.

The problem surfaced when the bootloader in Peach-pit board set
the EPLL clock as the parent of AUDSS mux. While booting the kernel,
we used to get a system hang during late boot if CLK_MAU_EPLL was
disabled.

Signed-off-by: Tushar Behera <tushar.b@samsung.com>
Signed-off-by: Shaik Ameer Basha <shaik.ameer@samsung.com>
Reported-by: Kevin Hilman <khilman@linaro.org>
Tested-by: Javier Martinez Canillas <javier.martinez@collabora.co.uk>
Tested-by: Doug Anderson <dianders@chromium.org>
Signed-off-by: Kukjin Kim <kgene.kim@samsung.com>