ARM: dts: exynos: Enable Mixer node for Exynos5800 Peach Pi machine

Commit 1cb686c0 ("ARM: dts: exynos: Add status property to Exynos 542x
Mixer nodes") disabled the Mixer node by default in the DTSI and enabled
for each Exynos 542x DTS. But unfortunately it missed to enable it for the
Exynos5800 Peach Pi machine, since the 5800 is also an 542x SoC variant.

Fixes: 1cb686c0 ("ARM: dts: exynos: Add status property to Exynos 542x Mixer nodes")
Signed-off-by: Javier Martinez Canillas <javierm@redhat.com>
Acked-by: Marek Szyprowski <m.szyprowski@samsung.com>
Tested-by: Guillaume Tucker <guillaume.tucker@collabora.com>
Signed-off-by: Krzysztof Kozlowski <krzk@kernel.org>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>