arm64: dts: exynos: Assign parent clock of the clkout clock for TM2 board

Without this patch the clkout clock is orphaned and sound doesn't
work properly.

Signed-off-by: Sylwester Nawrocki <s.nawrocki@samsung.com>
Signed-off-by: Marek Szyprowski <m.szyprowski@samsung.com>
Reviewed-by: Sylwester Nawrocki <s.nawrocki@samsung.com>
Signed-off-by: Krzysztof Kozlowski <krzk@kernel.org>