regulator: cros-ec: Constify cros_ec_regulator_voltage_ops

It is never modified, so make it const to allow the compiler to put it
in read-only memory.

Signed-off-by: Rikard Falkeborn <rikard.falkeborn@gmail.com>
Acked-by: Pi-Hsun Shih <pihsun@chromium.org>
Link: https://lore.kernel.org/r/20200711114409.9911-1-rikard.falkeborn@gmail.com
Signed-off-by: Mark Brown <broonie@kernel.org>

drivers/regulator/cros-ec-regulator.c

@@ -142,7 +142,7 @@ static int cros_ec_regulator_set_voltage(struct regulator_dev *dev, int min_uV,
 			   sizeof(cmd), NULL, 0);
 }
 
-static struct regulator_ops cros_ec_regulator_voltage_ops = {
+static const struct regulator_ops cros_ec_regulator_voltage_ops = {
 	.enable = cros_ec_regulator_enable,
 	.disable = cros_ec_regulator_disable,
 	.is_enabled = cros_ec_regulator_is_enabled,