ARM: dts: imx25: drop incorrect reg in fixed regulators

Fixed regulators are not in some bus and bindings do not allow a "reg"
property.  Move them out of "regulators" node to top-level.

Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Signed-off-by: Shawn Guo <shawnguo@kernel.org>