Use hyphens instead of underscores in the Exynos5433 node names which is
expected by naming convention, multiple dtschema files and pointed out
by dtc W=2 builds.

Signed-off-by: Krzysztof Kozlowski <krzk@kernel.org>
Link: https://lore.kernel.org/r/20201105184506.215648-6-krzk@kernel.org