Add USB VBUS regulator for RZ/G2L

Merge series from Biju Das <biju.das.jz@bp.renesas.com>:

As per RZ/G2L HW manual, VBUS enable can be controlled by the VBOUT bit of
the VBUS Control Register(VBENCTL) register in the USBPHY Control. But
this IP is in the Reset block.

Reset driver exposes this register as regmap and instantiate the USB VBUS
regulator device. Consumers(phy device) can use regulator APIs to control
VBUS as controlling is done in the atomic context using a new API which
is added for the purpose.

include/linux/regulator/consumer.h

@@ -250,6 +250,7 @@ int regulator_get_hardware_vsel_register(struct regulator *regulator,
 					 unsigned *vsel_mask);
 int regulator_list_hardware_vsel(struct regulator *regulator,
 				 unsigned selector);
+int regulator_hardware_enable(struct regulator *regulator, bool enable);
 
 /* regulator notifier block */
 int regulator_register_notifier(struct regulator *regulator,
@@ -571,6 +572,12 @@ static inline int regulator_list_hardware_vsel(struct regulator *regulator,
 	return -EOPNOTSUPP;
 }
 
+static inline int regulator_hardware_enable(struct regulator *regulator,
+					    bool enable)
+{
+	return -EOPNOTSUPP;
+}
+
 static inline int regulator_register_notifier(struct regulator *regulator,
 			      struct notifier_block *nb)
 {