regulator: twl: Constify regulator_ops

These regulator_ops variables never need to be modified, make them const so
compiler can put them to .rodata.
Signed-off-by: Axel Lin <axel.lin@ingics.com>
Signed-off-by: Mark Brown <broonie@kernel.org>

drivers/regulator/twl-regulator.c

@@ -392,7 +392,7 @@ static int twl4030ldo_get_voltage_sel(struct regulator_dev *rdev)
 	return vsel;
 }
 
-static struct regulator_ops twl4030ldo_ops = {
+static const struct regulator_ops twl4030ldo_ops = {
 	.list_voltage	= twl4030ldo_list_voltage,
 
 	.set_voltage_sel = twl4030ldo_set_voltage_sel,
@@ -430,14 +430,14 @@ static int twl4030smps_get_voltage(struct regulator_dev *rdev)
 	return vsel * 12500 + 600000;
 }
 
-static struct regulator_ops twl4030smps_ops = {
+static const struct regulator_ops twl4030smps_ops = {
 	.set_voltage	= twl4030smps_set_voltage,
 	.get_voltage	= twl4030smps_get_voltage,
 };
 
 /*----------------------------------------------------------------------*/
 
-static struct regulator_ops twl4030fixed_ops = {
+static const struct regulator_ops twl4030fixed_ops = {
 	.list_voltage	= regulator_list_voltage_linear,
 
 	.enable		= twl4030reg_enable,