regulator: vexpress: Constify regulator_ops

vexpress_regulator_ops_ro and vexpress_regulator_ops are never changed,
make them const.

Signed-off-by: Axel Lin <[e-mail]>
Acked-by: Sudeep Holla <[e-mail]>
Signed-off-by: Mark Brown <[e-mail]>

drivers/regulator/vexpress-regulator.c

···
 	return regmap_write(reg->regmap, 0, min_uV);
 }
 
-static struct regulator_ops vexpress_regulator_ops_ro = {
+static const struct regulator_ops vexpress_regulator_ops_ro = {
 	.get_voltage = vexpress_regulator_get_voltage,
 };
 
-static struct regulator_ops vexpress_regulator_ops = {
+static const struct regulator_ops vexpress_regulator_ops = {
 	.get_voltage = vexpress_regulator_get_voltage,
 	.set_voltage = vexpress_regulator_set_voltage,
 };