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/drivers/regulator/core.c b/drivers/regulator/core.c
index 0f65b24..571ce0f 100644
--- a/drivers/regulator/core.c
+++ b/drivers/regulator/core.c
@@ -2074,10 +2074,20 @@
  */
 int regulator_set_voltage_sel_regmap(struct regulator_dev *rdev, unsigned sel)
 {
+	int ret;
+
 	sel <<= ffs(rdev->desc->vsel_mask) - 1;
 
-	return regmap_update_bits(rdev->regmap, rdev->desc->vsel_reg,
+	ret = regmap_update_bits(rdev->regmap, rdev->desc->vsel_reg,
 				  rdev->desc->vsel_mask, sel);
+	if (ret)
+		return ret;
+
+	if (rdev->desc->apply_bit)
+		ret = regmap_update_bits(rdev->regmap, rdev->desc->apply_reg,
+					 rdev->desc->apply_bit,
+					 rdev->desc->apply_bit);
+	return ret;
 }
 EXPORT_SYMBOL_GPL(regulator_set_voltage_sel_regmap);