Add pmic / regulator nodes to Mele M9 dts.

Note both reg_usb1_vbus and reg_dldo4 need to be on for the hub attached
to usb1 to work, and we can list only one usb1_vbus-supply, so dldo4 is
marked as regulator-always-on.
Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Maxime Ripard <maxime.ripard@free-electrons.com>