regmap: Clean up _regmap_update_bits()

Since sometimes the 'config' parameter has no use, it should be NULL.
And make the code simplifier.
Signed-off-by: Xiubo Li <Li.Xiubo@freescale.com>
Signed-off-by: Mark Brown <broonie@linaro.org>

drivers/base/regmap/regmap.c

@@ -1969,9 +1969,11 @@ static int _regmap_update_bits(struct regmap *map, unsigned int reg,
 
 	if (tmp != orig) {
 		ret = _regmap_write(map, reg, tmp);
-		*change = true;
+		if (change)
+			*change = true;
 	} else {
-		*change = false;
+		if (change)
+			*change = false;
 	}
 
 	return ret;
@@ -1990,11 +1992,10 @@ static int _regmap_update_bits(struct regmap *map, unsigned int reg,
 int regmap_update_bits(struct regmap *map, unsigned int reg,
 		       unsigned int mask, unsigned int val)
 {
-	bool change;
 	int ret;
 
 	map->lock(map->lock_arg);
-	ret = _regmap_update_bits(map, reg, mask, val, &change);
+	ret = _regmap_update_bits(map, reg, mask, val, NULL);
 	map->unlock(map->lock_arg);
 
 	return ret;
@@ -2019,14 +2020,13 @@ EXPORT_SYMBOL_GPL(regmap_update_bits);
 int regmap_update_bits_async(struct regmap *map, unsigned int reg,
 			     unsigned int mask, unsigned int val)
 {
-	bool change;
 	int ret;
 
 	map->lock(map->lock_arg);
 
 	map->async = true;
 
-	ret = _regmap_update_bits(map, reg, mask, val, &change);
+	ret = _regmap_update_bits(map, reg, mask, val, NULL);
 
 	map->async = false;