regmap: allow const array for {devm_,}regmap_field_bulk_alloc reg_fields

The reg_fields array fed to {devm_}regmap_field_bulk_alloc is currently
not const, which is not correct on semantics (the functions shouldn't
change reg_field contents) and prevents pre-defined const reg_field
array to be used.

As the implementation of this function doesn't change the content of it,
just add const to its prototype.

Signed-off-by: Icenowy Zheng <icenowy@sipeed.com>
Link: https://lore.kernel.org/r/20210802063741.76301-1-icenowy@sipeed.com
Signed-off-by: Mark Brown <broonie@kernel.org>

drivers/base/regmap/regmap.c

@@ -1298,7 +1298,7 @@ EXPORT_SYMBOL_GPL(devm_regmap_field_alloc);
  */
 int regmap_field_bulk_alloc(struct regmap *regmap,
 			    struct regmap_field **rm_field,
-			    struct reg_field *reg_field,
+			    const struct reg_field *reg_field,
 			    int num_fields)
 {
 	struct regmap_field *rf;
@@ -1334,7 +1334,7 @@ EXPORT_SYMBOL_GPL(regmap_field_bulk_alloc);
 int devm_regmap_field_bulk_alloc(struct device *dev,
 				 struct regmap *regmap,
 				 struct regmap_field **rm_field,
-				 struct reg_field *reg_field,
+				 const struct reg_field *reg_field,
 				 int num_fields)
 {
 	struct regmap_field *rf;

include/linux/regmap.h

@@ -1269,12 +1269,13 @@ void devm_regmap_field_free(struct device *dev,	struct regmap_field *field);
 
 int regmap_field_bulk_alloc(struct regmap *regmap,
 			     struct regmap_field **rm_field,
-			     struct reg_field *reg_field,
+			     const struct reg_field *reg_field,
 			     int num_fields);
 void regmap_field_bulk_free(struct regmap_field *field);
 int devm_regmap_field_bulk_alloc(struct device *dev, struct regmap *regmap,
 				 struct regmap_field **field,
-				 struct reg_field *reg_field, int num_fields);
+				 const struct reg_field *reg_field,
+				 int num_fields);
 void devm_regmap_field_bulk_free(struct device *dev,
 				 struct regmap_field *field);