regulator: core: Allow specify apply_[reg|bit] for regmap based voltage_sel operations

Some DVM regulators needs to update apply_bit after setting vsel_reg to
initiate voltage change on the output.  This patch adds apply_reg and
apply_bit to struct regulator_desc and update
regulator_set_voltage_sel_regmap() to set apply_bit of apply_reg when
apply_bit is set.

Signed-off-by: Axel Lin <axel.lin@ingics.com>
Signed-off-by: Mark Brown <broonie@opensource.wolfsonmicro.com>
diff --git a/include/linux/regulator/driver.h b/include/linux/regulator/driver.h
index d10bb0f..23070fd 100644
--- a/include/linux/regulator/driver.h
+++ b/include/linux/regulator/driver.h
@@ -193,6 +193,10 @@
  *
  * @vsel_reg: Register for selector when using regulator_regmap_X_voltage_
  * @vsel_mask: Mask for register bitfield used for selector
+ * @apply_reg: Register for initiate voltage change on the output when
+ *                using regulator_set_voltage_sel_regmap
+ * @apply_bit: Register bitfield used for initiate voltage change on the
+ *                output when using regulator_set_voltage_sel_regmap
  * @enable_reg: Register for control when using regmap enable/disable ops
  * @enable_mask: Mask for control when using regmap enable/disable ops
  *
@@ -218,6 +222,8 @@
 
 	unsigned int vsel_reg;
 	unsigned int vsel_mask;
+	unsigned int apply_reg;
+	unsigned int apply_bit;
 	unsigned int enable_reg;
 	unsigned int enable_mask;
 	unsigned int bypass_reg;