Currently the regulator-suspend-min/max-microvolt must be within the
root regulator node but the dt-bindings specifies it as subnode
properties for the regulator-state-[mem/disk/standby] node. The only DT
using this bindings currently is the at91-sama5d2_xplained.dts and this
DT uses it correctly. I don't know if it isn't tested but it can't work
without this fix.