regulator: pbias-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/pbias-regulator.o
   text	   data	    bss	    dec	    hex	filename
   2545	    624	      0	   3169	    c61 regulator/pbias-regulator.o

File size after: drivers/regulator/pbias-regulator.o
   text	   data	    bss	    dec	    hex	filename
   2801	    368	      0	   3169	    c61 regulator/pbias-regulator.o

Signed-off-by: Bhumika Goyal <bhumirks@gmail.com>
Signed-off-by: Mark Brown <broonie@kernel.org>

drivers/regulator/pbias-regulator.c

@@ -54,7 +54,7 @@ static const unsigned int pbias_volt_table[] = {
 	3000000
 };
 
-static struct regulator_ops pbias_regulator_voltage_ops = {
+static const struct regulator_ops pbias_regulator_voltage_ops = {
 	.list_voltage = regulator_list_voltage_table,
 	.get_voltage_sel = regulator_get_voltage_sel_regmap,
 	.set_voltage_sel = regulator_set_voltage_sel_regmap,