ARM: dts: exynos: Add missing used PMIC regulators on Exynos5422 Odroid boards

Define LDO2, LDO23 and LDO27 critical board regulators to describe the
hardware.

Suggested-by: Joonyoung Shim <jy0922.shim@samsung.com>
Signed-off-by: Krzysztof Kozlowski <krzk@kernel.org>