+MMC power
+---------
+
+Controllers may implement power control from both the connected cards and
+the IO signaling (for example to change to high-speed 1.8V signalling). If
+the system supports this, then the following two properties should point
+to valid regulator nodes:
+
+- vqmmc-supply: supply node for IO line power
+- vmmc-supply: supply node for card's power
+