mfd: tps6586x: move regulator dt parsing to regulator driver

Moving regulator node parsing to regulator driver in place
of parsing it on mfd driver.
The motivation for this change are:
- MFD core driver should not depends on regulator and able
  to instantiate device without regulator.
- The API for matching regulators are in regulator core and
  it is good that regulator driver only calls this API.
- Regulator specific support should be in regulator driver only
  to ease any enhancement/modification for regulators.
- The regulator driver is now registered as mfd sub device and
  all regulator registration is done from single probe call.

Signed-off-by: Laxman Dewangan <ldewangan@nvidia.com>
Signed-off-by: Mark Brown <broonie@opensource.wolfsonmicro.com>
diff --git a/include/linux/mfd/tps6586x.h b/include/linux/mfd/tps6586x.h
index 2dd1231..f8da0e1 100644
--- a/include/linux/mfd/tps6586x.h
+++ b/include/linux/mfd/tps6586x.h
@@ -29,6 +29,7 @@
 	TPS6586X_ID_LDO_8,
 	TPS6586X_ID_LDO_9,
 	TPS6586X_ID_LDO_RTC,
+	TPS6586X_ID_MAX_REGULATOR,
 };
 
 enum {
@@ -79,6 +80,8 @@
 	int gpio_base;
 	int irq_base;
 	bool pm_off;
+
+	struct regulator_init_data *reg_init_data[TPS6586X_ID_MAX_REGULATOR];
 };
 
 /*