regulator: s5m8767a: Support AP watchdog reset operation

The S5M8767A can't know status of ap reset.
So, After AP watchdog reset, AP can't boot normally.

Problem can be happened like below condition.
- AP Bootable lowest voltage(vdd_arm): 0.9v
- AP DVFS voltage table: 0.8v, 0.9v, 1.0v
- During AP works on lowest voltage(0.8V), watchdog reset is asserted
- AP can't boot, because vdd arm is still 0.8v

Solution
- Basic concept:
  After ap watchdog reset, GPIO configuration is changed by default value
- S5M8767A has function of voltage control with gpio (8 levels with 3 gpios)
- Set bootable voltage on level 0 -> can work with default gpio configuration
- In the probing, Change voltage control level from level 0 to level 1
- Execute normal dvfs operation on level 1
- After watchdog reset, ap gpio is set by default value
- PMIC operation mode is changed by ap reset (level1 -> level0)
- Regardless of previous vdd_arm voltage, AP always can be booted.

Signed-off-by: Sangbeom Kim <sbkim73@samsung.com>
Signed-off-by: Mark Brown <broonie@opensource.wolfsonmicro.com>

include/linux/mfd/s5m87xx/s5m-core.h

@@ -347,6 +347,7 @@ struct s5m_platform_data {
 	bool				buck_voltage_lock;
 
 	int				buck_gpios[3];
+	int				buck_ds[3];
 	int				buck2_voltage[8];
 	bool				buck2_gpiodvs;
 	int				buck3_voltage[8];
@@ -369,6 +370,10 @@ struct s5m_platform_data {
 	bool                            buck2_ramp_enable;
 	bool                            buck3_ramp_enable;
 	bool                            buck4_ramp_enable;
+
+	int				buck2_init;
+	int				buck3_init;
+	int				buck4_init;
 };
 
 #endif /*  __LINUX_MFD_S5M_CORE_H */