ARM: dts: exynos: Define fixed regulators in root node for consistency in Origen

Remove the regulators node and define fixed regulators directly under
the root node.  This makes Exynos4412 Origen board consistent with other
Exynos boards.

Suggested-by: Marek Szyprowski <m.szyprowski@samsung.com>
Signed-off-by: Krzysztof Kozlowski <krzk@kernel.org>