regulator: aat2870-regulator: constify regulator_ops structure

Declare regulator_ops structure as const as it is only stored in the ops
field of a regulator_desc structure. This field is of type const, so
regulator_ops structures having this property can be made const too.

File size before: drivers/regulator/aat2870-regulator.o
   text	   data	    bss	    dec	    hex	filename
    938	   1424	      0	   2362	    93a regulator/aat2870-regulator.o

File size after: drivers/regulator/aat2870-regulator.o
   text	   data	    bss	    dec	    hex	filename
   1194	   1168	      0	   2362	    93a regulator/aat2870-regulator.o
Signed-off-by: Bhumika Goyal <bhumirks@gmail.com>
Signed-off-by: Mark Brown <broonie@kernel.org>

drivers/regulator/aat2870-regulator.c

@@ -97,7 +97,7 @@ static int aat2870_ldo_is_enabled(struct regulator_dev *rdev)
 	return val & ri->enable_mask ? 1 : 0;
 }
 
-static struct regulator_ops aat2870_ldo_ops = {
+static const struct regulator_ops aat2870_ldo_ops = {
 	.list_voltage = regulator_list_voltage_table,
 	.map_voltage = regulator_map_voltage_ascend,
 	.set_voltage_sel = aat2870_ldo_set_voltage_sel,