ARM: dts: imx6qdl-hummingboard2: rename regulators to match schematic

Make the regulators match the schematic - name the regulators after
one of their schematic supply names, and arrange them into their
heirarchy.

Signed-off-by: Russell King <rmk+kernel@armlinux.org.uk>
Reviewed-by: Fabio Estevam <fabio.estevam@nxp.com>
Signed-off-by: Shawn Guo <shawnguo@kernel.org>