mfd: Allow mapping regulator supplies to MFD device from children

Occasionally, it is useful to map supplies from a child device onto the
MFD device. A typical usecase for this would be if the MFD device is
represented as a single node in device tree. All supplies will be
defined in device tree as existing on the MFD device. When a child
depends on frameworks which might have no knowledge of MFD to lookup
supplies on its behalf the supply will not be found.

This patch adds a list of supplies that should be looked up on the
parent rather than the child as part of the mfd_cell structure.

Signed-off-by: Charles Keepax <ckeepax@opensource.wolfsonmicro.com>
Acked-by: Lee Jones <lee.jones@linaro.org>
Signed-off-by: Mark Brown <broonie@linaro.org>

include/linux/mfd/core.h

@@ -59,6 +59,12 @@ struct mfd_cell {
 	 * pm_runtime_no_callbacks().
 	 */
 	bool			pm_runtime_no_callbacks;
+
+	/* A list of regulator supplies that should be mapped to the MFD
+	 * device rather than the child device when requested
+	 */
+	const char		**parent_supplies;
+	int			num_parent_supplies;
 };
 
 /*