ARM: dts: imx6qdl-sabresd: Move regulators outside of "simple-bus"

It is not recommended to place regulators inside "simple-bus", so move
them out to make it cleaner the addition of new regulators.

Signed-off-by: Fabio Estevam <festevam@gmail.com>
Signed-off-by: Shawn Guo <shawnguo@kernel.org>