ARM: dts: add dependency between TV and LCD0 power domains for exynos4

TV Mixer needs both TV and LCD0 domains enabled to be fully operational.
This dependency is modelled by making TV power domains a sub-domain of
LCD0 power domain.

Signed-off-by: Marek Szyprowski <m.szyprowski@samsung.com>
Signed-off-by: Kukjin Kim <kgene@kernel.org>